GT250 EFI DSpec Stalls at Idle after Warm Up
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I own the above mentioned bike bought second hand from the original owner who had purchased it in 2013. When I bought it, it was still under warranty with about 3000km on the clock. It is important to note that this version, the DSpec, has some minor differences in the number of sensors than similar GT250’s of that period. It is a twin cylinder equipped with Delphi electronics. The bike, which is always garaged, worked flawlessly for the first couple of years but after that it had started to loose power erratically after warm up. This was happening after about 15mins of starting from cold. From time to time I was also getting error code 132 intermittently which indicated problems on cylinder one. When the O2 sensor was inspected it was found to be covered in soot. Because of this I had assumed that the problem was limited to around cylinder 1. I replaced the plugs and high voltage cables and also swapped the coils and the O2 sensors around but the problem did not seem to change or move. I also had the injectors cleaned up by an experienced bike mechanic. I was also lucky to find a nearly new ECU which I could purchase at half price, but even this did not improve the situation.
Finally I decided to replace the coils which solved the problem completely.
Unfortunately a few more years down the line I am starting to experience a similar, though not so drastic situation so far with the bike starting perfectly but after warm up it starts missing occasionally at idle and if I stay at idle long enough the engine stalls. I don’t feel any loss in power when I am revved up.
Because of this I am starting to suspect the coils again even though these are no more than 3 years old.
Any ideas?
Regards
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Clean all the connections you can find, there is one if I remember rightly in the loom on the left hand side looking from the back forwards it’s hidden by the air box this takes the signal from the coil it can cause the issue as the ECU miss reads the rpm. Hyosungs really have bad connection issues.
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Thank you Simon for your contribution. I will go through all my connections and look for bad contacts. In the past I have replaced one or 2 connectors, the most awkward one being the one just under the steering column which feeds the instrument panel.
However given the fact that the bike starts flawlessly at cold and only exhibit these symptoms after warming up I don’t think bad contacts would cause this particular problem. I would expect to have problems even at cold. I also am able to read all the data coming out of the ECU and am able to display all the parameters for the bike run, in spreadsheet. I have compared data coming out at when running at cold to data coming out just before a stall and I don’t see much difference in the patterns.
regards
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Here is some data I collected from the ECU just before it stalled(rows around 112). The engine temp was about 112 C while the temp at the manifold around 50C.
I also have some question marks about the Idle Speed Controller. According to the manual when the unit is removed from the airbox, the piston should be fully in when key is off and fully out when the key is turned on. In my case it stays closed in both conditions but when i turn the key back off the piston extends for about 2 secs and then retracts completely. I don’t know what to make of this. My logic tells me that the piston should only starts moving out to restrict the air, AFTER the engine has started.
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I have not seen an ISC dismantled but from the sound it makes when it is in operation and the fact that the “piston” is fitted to a threaded rod leads me to think that the ISC is a stepper motor with a “nut” fitted to its rotor. As the motor spins clockwise or anticlockwise the “nut” rotates with it, causing the threaded rod to move in or out accordingly. Even though there is a spring which acts to push out the “piston” it is not strong enough to do so. Below is an extract from the manual about the ISC. The manual calls it a solenoid but it does not sound like one.
The reported fault code is a strange one. First of all the manual does not mention any fault code 306. Also that is a fault code from a previous run not this one. I have removed the column containing the current fault code to simplify the chart and in any case because all the entries in that column were zero.
I think the line which indicates an actual misfire is line 102 which shows the RPM dipping to 1515. The injector figures which are actually the time in milliseconds that the injectors remain open seem stable to me and only double right after the engine stalls at around line 111. I think that was a last gasp attempt by the ECU to get the engine to rev up again.
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@Simon, Here is some data I collected from the ECU just before it stalled(rows around 112). The engine temp was about 112 C while the temp at the manifold around 50C. I also have some question marks about the Idle Speed Controller. According to the manual when the unit is removed from the airbox, the piston should be fully in when key is off and fully out when the key is turned on. In my case it stays closed in both conditions but when i turn the key back off the piston extends for about 2 secs and then retracts completely. I don’t know what to make of this. My logic tells me that the piston should only starts moving out to restrict the air, AFTER the engine has started.
Hello, Joe.
How do you collected the ECU log? i’m very interested but i don’t find the cable to conect to ECU.
Thanks.
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The way to tackle data collection depends on whether you are proficient in electronics or not. In either case you will need to download a program freely available on the internet from https://netcult.ch/elmue/HUD%20ECU%20Hacker/. This help file is a must read. Further down you will find a link from where to download the actual program. This program is very professionally written and complete. Its only drawback for me is that is works only in windows and since I am a Linux user I opted to write my own using python and that help file.
In terms of hardware you can use the Blue interface cheaply available from Ebay or Aliexpress (search for VAG KKL; cost around €5) and solder a 3 wire wires from inside the interface to a 4 wire connector which goes on the Hyosung. This is an easy job. I had ordered this interface but since it takes 4 or 5 weeks for items from China to come to me, I opted to build my own in the meantime using a standard USB to Serial converter I had around. This would be the black thing to the left of the picture. Both work well.
(Note to the Administrator: for some reason I am unable to attach a photo or even paste a screenshot into my reply. This was not a problem in the past)
Don’t hesitate to contact me if you need help.
Regards
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I have been looking for that interface, or a diagram of it, for weeks. I have the typical cheap bluetooth-OBD interface used in several cars, but the only interface i found, called “BHY02”, was ridicously expensive.
Unfortunately, seems like your bike is the DELPHI ECU versión (the one witch double coupler), while mine is the DAEWOO versión. I will that this ECU can work witck K-line protocol , and I will read that link; by the way, a schem witch the colors and function of your motorbike’ diagnostic coupler would be happily welcome
Anyway, thanks for your answer, and the link!!
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after mining that web, i have seen the the daewoo ECU looks similar to BOSCH MSE6.0 ECU used in benelli TRK 502, maybe I can still connect it!
It has same 48-pin coupler, and many pins have the same function.
edit: i have been a little unpolite… Did you found the trouble with your bike? mine has simillar stalling, in medium RPM regime (3000-7000)
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Searching the aliexpress site for “VAG KKL” came up with this: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20220928215901&SearchText=vagkkl&spm=a2g0o.home.1000002.0
I would not spend too much money on this. Also I would not trust bluetooth. Bluetooth seems to work well for audio connections but I have not succeeded in sending or receiving standard data in my experimentation. To connect to the 4 wire connector all you need are 3 wires: +12v, gnd and K-line. I drilled a small hole in the side of the interface and soldered directly to the pins. Pad sizes are large enough so you don’t need to be an expert to do this.
I still cannot attach photos to this forum but if you want to send me your email I can send directly.
The program I suggested works with the Delphi MC05 ECU which was fitted to Hyosung from 2012 onwards. I am not sure if it will work with the DAEWOO version. I suggest you contact the program writer for a more informed reply on this. I have communicated with him several times and he was quite helpful.
Your bike interface is probably K-line but the commands to extract data will probably be different. For example my Kymco bike also has a k-line interface but the commands are totally different. Waking up the ECU is quite standard but then you have to do some reverse engineering to extract useful data from the ECU.
I have replace coil no.1 on my bike and so far it is working well. This is the second time this has happened so am note sure what is causing this coil to fail repeatedly. Note that all the ECU software will probably not help with the problem I had since the ECU does not monitor the spark directly. Its only feedback is from the O2 sensor which will not detect any intermittent failure on the secondary side of the coil.
Regards
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Maybe some “temperature insulation” could help on ignition coils conservation. I think they get really hot, at least in gv250 situation, beside cilinder under fuel tank. this engine gets really hot, and perhaps heat acumulates at low speed. I don’t know where gt250 has these coils installed…
I had temp related issue with spark plug caps, and replacing them with ngk ones get solved it (misfire in idle when engine was warm) but now have stalling in medium rpm range… but I’m thinking that is related to ECU main coupler, because when I move it a little changes engine behavior at idle. I have ensured coupler and ECU unit with a plastic tie, after cleaning this coupler and ECU pins with contact cleaner, and today worked well…i will keep watching.
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On the GT250, the coil for cylinder 1 is mounted just behind the oil cooler at the steering post. The second coil is installed on the inside of the left hand side frame just under the petrol tank. This engine does really get very hot being air cooled. Mine reaches at least 112C when outside temperature is above 30C. However when I put my hands on either coil after a long run I don’t get the impression they get hot at all, at least on the outside. Just bearably warm.
Regarding connectors, my 2013 bike has a mix of connectors installed. The ones installed on the engine electrics including the ECU seem pretty good and water tight. The rest are rather mediocre. They are not water tight at all and not even gold plated. Unfortunately two of these are the connector for the 15A fuse and as well as that for the main relay. The +12V feeding the ECU and the other engine electrics comes off these 2 components which seems rather stupid to me. To make matters worse the wire used to carry this 12V supply seems ridiculously thin to me.
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I suspect of some loosy contact in ECU conector, perhaps a hand of electric-conductive paint could help.
ECU conector is like this:
https://es.aliexpress.com/item/32919319794.html
it has internal silicone but is corrupt, while ECU pins have some wearing. when I move the ECU, engine idle is up-down-up, what is very weird…
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Those connectors are quite similar to the ones I have which seem to me of good quality. When I refer to cheap connectors I mean this type:
These are ok in areas that don’t see high humidity or moisture but are totally unsuitable on a car; even more on a bike.
I would not recommend conductive paint.
If you are certain that moving the ECU about alters the idling I would try to push/pull each individual wire of the connectors to see if the behavior is replicated. I know this is easier said than done on a bike due to lack of space.
Also liberal use of contact cleaner is suggested but you probably have already tried that.
Incidentally are you sure that your GV250 EFI (2011) is a DSpec version? The electrical diagram in the Dspec manual I have, corresponds exactly to a Delphi ECU (MC05)
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no, it is no Dspec, it is “FI” version. I used this service manual for diagram, electrical diagnostic and error coding. :
http://www.hyosung.hu/download/pdf/data/service-manual/GV250-GT250-EFI-service-manual.pdf
Yes, i wear the contac cleaner in the top case
, because first week the bike didn’t start twice in street, and contact cleaning of ECU conector solved it (this is when I saw that silicone of the conector had become like sand). But now for 2 months it has been working right except for that eventual stalling between 3-7k rpm.Anyway the top speed (about 140 in the clock, 129real) and mileage (about 4,3 l/100km) is fine for me (1’93 and 120kg), and the spark electrode color is like coffe… this is why i wanted to collect the ECU data for searching the mismatching injection at mid range.
I will try to find the cable(s) that is(are) making that bad contact,, thank you 🙂
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Sorry, I mistaked the file of the link, the service manual of my fike is this (EI version):
https://drive.google.com/file/d/19mnUqXh8Z5VcL8wQ1pvWdD9KM5p3NdM1/view?usp=sharing
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That is, yet another version of the Hyosung bike manual. The version of the manual I have which most resembles your GV250 has a 34 pin connector to the ECU and a 5 pin connector for the CAN TOOL instead of the usual 4.
P.S. Just noted that in fact the manual is the same as the one you proposed in the earlier mail.
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Hi, I’m having the same problem with my Hyosung Gt250R (DELPHI ECU). Could you send me photos of the cable you made? My email is [admin redacted] Thanks in advance, Cristian
Hey 🙂
As it is a public site , i had to remove your email to protect your privacy.
Also the member you want has a new account, you can PM him here
https://hyoriders.club/members/jfarr/You can always create a brand new topic with as much detail as you can past and present history, it will help us understand the situation better , that is if you need us.
If i do not reply quickly , usually Simon who also has an EFi Hyosung knows how they behave and will offer insight 🙂 -
@Cristian,
The attached picture shows the 2 cables I have built. Both work fine and the only reason I build the one on the left is, I got impatient waiting for the delivery of the Blue interface (KKL VAG) which took more than a month to get here from China.
The one on the left was build around a standard rs232usb interface using the circuit supplied from the website I referred too above.
The one on the right is simpler to wire up. The connector has the auto standard 16 pin connector but in reality the circuit inside only has connections to 4 pins. These are;
1. +12V
2. GND
3. K+ data line
4. K- data lineThe Delphi ECU on the Hyosung only uses the first 3. I am not certain if older versions of the bike use different protocols but I am almost sure it is the same.
Connection to the actual pads was made by inserting 3 wires through a small hole I drilled in the connector blue cover. Soldering is fairly easy since the pads on the PCB are fairly large.
The main issue I found was finding the connector to the bike itself since I could not find a suitable 4 pin connector locally. The ones available here are 4 pin but with different dimensions.
I hope this helps. Don’t hesitate to ask if you have further questions.
Regards
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Thank you very much Joseb,
As I can see you have in your description a Kline + and a Kline -, but in the diagrams in the web site there’s only three wires, two for power and one for Kline.
Also it’s hard for me to identify the pin one on the connector from my bike. Could you tell me te colors of the cables from the bike? My bike has an MT05 DELPHIE ECU.
Regards,
Cristian
PD: the bike is at the service shop right now, and they tell me that an injector is suspicious. But I’m not sure if an injector can fail under temperature, and I can’t find the original injector in my country…
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Important: the Kline- pin is ONLY available on the BLUE interface. Not on the bike. I only mentioned it just in case you intend to buy one like it and solder on it the 3 wires.
As for the bike connector, the 2 black wires are the ground, the red wire is 12.5V the blue wire is Kline+. If still in doubt it is very easy to find which is which using a multimeter. You should find +12V between the red wire and any of the 2 black wires. The polarity is important and also note that 12V is always available on this connector even with the key switch in the OFF position. The below photos should help.
Re the suggestion that the issue is injector, this is of course possible. Did this technician explain why? I would be interested to hear what he has to say. From my own experience it is more likely that the issue are the coils. I have so far replaced 2.
Good luck
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Hi,
Today I have scanned the bike. Just old DTCs of the lambdas voltage and injector 1 & 2 failure. I guess that the injector failures were during service at the shop. The technician told me that one of the injectors has rust in it (the gas tank has some rust). He only changed the spark plugs and caps, and cleaned the injectors.
I cleared the DTCs and keep the bike at idle for almost ten minutes with no failure at all with te temp reaching 110-120 C.Later I will go for a ride and update this post.
Regards,
Cristian
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Hi,
I have run into the exact same issue on my bike recently. I have new coils on the way, but also looking at diagnosing engine temperature sensor at the same time because the idle difference between cold start and warmup is very significant. Cold starts are super smooth and after warmup it struggles to stay alive and eventually stalls. Any update on your issue would be super helpful!
Regards,
Sam
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Hi,
Regretfully I have not solved the issue yet but given that I have another bike I can use I have not really been trying anyway.
Having said that, just last week I made another attempt as follows. I installed the tank temporarily about 200mm higher, removed the air cleaner and reconnected the tank with a longer pipe to the injectors. The 2 pipes from the carbs leading to the ISC were disconnected from the ISC side. When I started the bike in this condition, initially I noted that sometimes combustion was taking place under the carb 2 throttle. Eventually this disappeared but I was still getting some misses from the engine which coincided with back pressure coming out of cylinder 2 pipe. The only conclusion which comes to mind is that sometimes the inlet valves were not closing completely. I checked valve gaps but these appeared to be according to specs, right in the middle of the range.
I am currently dismantling the cylinder head to see if I have some issue with valve seating.
I don’t know if this issue is related to the original one but at the moment I have no further leads.
I am still interested in getting to the bottom of this problem and, if ok with you, I would like to collaborate with you to arrive at a solution.
In the meantime can you tell me from where you have sourced the coils and also how you intend to diagnose the temperature sensor?
Regards
joe
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Reading about your last attempt, I am assuming your bike is carbed. The symptoms that you have described could also be an issue with ignition timing. I am not sure how ignition timing is calculated in a carbed bike. Does your bike have an ECU? On a different note, these could also be symptoms of ISC lines being disconnected and throwing off the AFR.
I have sourced GV650 coils off of ebay, which are a little longer in size but have the same orientation of connectors and come with new plug cables and caps. (http://surl.li/sfsix)
I was unable to remove the temp sensor from the bike last night, for lack of a better tool. Once I get it removed, I want to check the voltage being produced by the sensor under different temperature settings and compare them to the default values given in the repair manual. Today I am doing a resistance test on my old coils and will update you on that soon.
Sam
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Update: In my scenario, it was one of the MAP/IAP sensors. I disconnected them one at a time, and after disconnecting the one on the right side, my idle dropped down to 1500 and the misfires disappeared! Ordering a new one now. Part number is 28084560. Hope this helps someone! I will update again after installing a new MAP/IAP.
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Hi Sam,
this is an attempt to comment on all your 3 mail.
My bike is an EFI system and it still has 2 carburettors. The carbs control the airflow while the ECU controls the rest. I therefore don’t understand what you mean by “carbed”. In my system, what is a bit disappointing to me is that the fuel injectors spray into the bottom end of the carburettors and not directly into the cylinder. While I don’t like it, this of course is not the reason for my problem.
Ignition timing is determined mechanically, by the timing chain plus cam shafts and electrically, via one pickup coil near the magneto together with the ECU. The pick up coil only generates one pulse per revolution so the ECU is the one which estimates at what point the 2 sets of injector and spark plug activate.
The valve clearance is according to spec and the cams are properly aligned with piston at TDC so this cannot be the reason why combustion is leaking back into the carb!
I have looked at the ebay coils you indicated. They are totally different to mine. Most important difference is the connector. Mine are Delphi as are most of the electrical components around the engine.
If you have a fault which only appears after the engine has completely warmed up then I am afraid measuring the DC resistance at cold may not point you to the fault. Mine too measured up properly at cold but I still was facing idling fails when hot.
I am glad to hear that you have found the culprit for your system. I would not have thought these to be the issue but then again I am just an amateur at bike repair.
Regards
Joe
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Sorry to hear that your problem remains.
You keep referring to MAP sensors but none of the manuals I have mention MAP. They do mention IAP though so I assume you are referring to these. It seems your bike has two IAP sensors. My bike which is the 2013 model (also referred to as the Dspec version) only has one.
Going back to your bike, with one IAP sensor off, the bike should be generating error C17 for IAP-1 or C18 for IAP-2. Which?
Also the voltage on the signal pin for these sensors should be 0.1V < sensor voltage < 4.8V. What is the value?
Also, seeing that you have 2 sensors, what happens if you swap the 2 around?
Also do you have the possibility of collecting data from the ECU?
I realise the above are not the solution. Just some avenues of analysis.
Regards
joe
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You’re right, I have two IAP sensors. The idle and low throttle sputtering disappears when I disconnect the right side IAP (IAP 2) and the FI light comes on. However, IAP 1 does not produce the same result when disconnected, FI light comes on and it ends up killing the engine anyway.
I will check the voltage on the sensor and the connector side soon.
It is hard to swap the sensors around because the sensors are in a very tight spot and requires removal of some fuel lines to access the 8mm bolt holding it in. It is a good idea though, and I will be trying it if the bike is apart.
I do have a VCDS cable (Blue FT32) that I use to scan my Audi, but I could not understand how I could use that cable to read data from my Hyosung.
Thank you for your input!
Regards,
Sam
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With the IAP-2 disconnected you should get the C18 error. Do you confirm this?
With IAP-2 disconnected and bike power turned on, check the voltages on the 3 wires of its terminal connection.
According to my manual, the resistance to ground(chassis) from the BW wire should be 0 ohms. The voltage on the OB wire should be between 4.5V and 5.5V. There is no value specified on the BY wire with the sensor disconnected. I would expect it to be zero.
Repeat measurements with sensor connected and compare. The value on the BY wire should be as stated previously.
I would also compare these figures with those on the IAP-1 sensor. Note that the equivalent to the BY will be BL.
Hopefully these measurements may lead you to a solution.
With regards to your VCDS cable it appears to be similar to the VAG-KKL cable. The software to go with it, which I had mentioned at the earlier in this thread, was written for the Delphi ECU MT05 so I am not sure if you can use it with your ECU. You need to check this.
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The voltage test checked out according to the instructions in the manual, so I came to thinking that sensor and wiring are good. My friend, who is a Honda technician, was hanging around around that time. I swapped the two IAP sensors around and problem stayed on cylinder 2! This guided us to think that something else is making the IAP sensor trip.
We had eliminated the possibility of vacuum leaks and fueling issues so fiddled around with the throttle body adjustment a little bit to adjust AFRs and the stalling/sputtering at hot idle disappeared. Idle came down to 1500 rpm. The issue has now moved to sputtering at take off, which disappears once the bike gets moving and goes above 5k rpm. Next move is to sync the throttle bodies (TBS) properly by using a throttle body synchronizer (manometer) to adjust throttle bodies at (1) idle and (2) 4000rpm. I will update you on how that works out.
If your throttle bodies are not in sync, engine may backfire, sputter, stall and misfire at different rpms, and this gets significantly worse as the engine warms up. That is one thing that you can check on your Hyosung if everything else checks out as should be.
Regards,
Sam
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Thank you very much Sam for a very, very interesting report. I would never have guessed that throttle misalignment would effect stalling/sputtering. May I ask if your bike model is the FI version? The reason I ask is that the manual I have, which I assumed applied to your bike, is for the 250FI. According to that manual, the 250FI has most of the sensors of the EFI models but NO TPS sensors. Strange.
Turning to my setup I am trying to understand how throttle misalignment can affect stalling at idle. The reason I say this is, at idle both throttle valves are completely closed and all the air needed for combustion at idle is led into the engine by means of 2 separate pipes feeding into the carbs at the engine side of the throttle valves. Air flow into these pipes is controlled by a single ISC motor. This to me implied that the throttle is completely bypassed at idle. Your report indicates otherwise.
I wonder how I can go about synchronising the carbs. I have no such equipment.
Regards
joe
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That is some good insight Joe. My bike is the 250 FI version. You’re right that I have two separate pipes running from the airbox into the engine side of the carbs. However, in my setup, the two nipples coming out of the ISC stepper motor are open and not connected to anything and the pipes coming from each carb are plugged into two separate nipples on the airbox that are blocked off from factory. Is this the same on your bike? (Did someone f up on my bike in the past?)
Basically, those two ports on the engine side of the carbs are blocked off at the airbox in my setup. The carbs are also cable driven, so there is independent adjustment possible on both. Due to this, both carbs can be at different positions at a certain rpm. While the bike is idling, and you change settings on each carb, you can hear the idle go up or down, rough up or smoothen out etc. To align them by ear, I zeroed out both carbs and started from scratch (the bike wouldn’t start at this point because there is no air getting into the cylinders) and then proceeded to open them up one rotation at a time on each side until the idle sounded healthy. The bike is running well for the most part right now with the IAPs plugged in, except some random bog/sputter when I open it up too quickly.
To fine tune it from here, I am making my own manometer using clear vinyl tubing, a long flat piece of cardboard, and some suitable fluid for the liquid inside. There are a lot of DIYs out there on how to make one at home, and its quite easy. It works off of vacuum and you plug it into the port on the engine side of the carbs to check which way the liquid is getting pulled more. It gives you a good visual of what’s going on in each carb/throttle body because doing it by the ear alone is inefficient and inaccurate.
This is what a homemade manometer looks like: (https://www.irv2.com/forums/attachment.php?attachmentid=112936&d=1448751314)
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Att: Administrator,
Earlier today I received a copy of a fresh comments written by Sam but when I log into the forum his message (#post-13005) does not show.
Att: Sam,
On my bike the ISC just has a piston which plunges into a hole into the air filter box. The 2 pipes from the carbs connect directly to the box right next to the ISC. The function of the ISC is to open an aperture from the air and allows a controlled amount of air to the 2 pipes.
Re the manometer, thanks for the link. There are also a lot of detail how to cheaply built one on Utube. The videos show the 2 manometer pipes connected to 2 special holes in the carbs or the cylinder head. I did not see any equivalent holes in my setup. The only 2 holes I see are the ones for the 2 pipes mentioned above.
Regards
Joe
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It has been approved , very sorry about that , it was the site’s security needing my attention to approve an unknown link you posted.
You can always copy and paste any pictures in to the forum, even make a tutorial if you like, i am sure it will help everyone that’s reading this topic
Regards ❤
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I took those two pipes and plugged them into the ports next to the ISC. I had to reset the throttle settings and close both the plates because the idle was going too high from the ISC and previously set throttle settings. Now the bike starts up right away and idles around 1600rpm, but the cylinder that was causing problems earlier cuts in and out, making the idle bounce to 1800 intermittently. The bike is not okay under load, bogs sputters and cuts out. I think I have made some progress by bringing the bike back to factory setup, but also back to square one at the same time 😆
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Att: Marcel,
No need to apologize. I guess I panicked. The decision to approve each message sent is commendable. Thank you for this service.
Att: Sam,
The decision to close the plates completely at idling makes sense to me since this allows the ECU to set airflow based solely on the ISC solenoid. If your idling speed is not stabilising yo may want to investigate the movements of the ISC.
Here is a photo a jig I set up to view the movements of the ISC. The reason this is needed is because since air intake at idling is not restricted the ECU will attempt to push out the ISC piston in an attempt to reduce airflow and therefore engine idling speed.
Whilst experimenting I also noted that my fuel injector number 2 had some small black particles lodged at the bottom end which is of course not good and may lead to misfiring. This led me to the fuel pump a picture of which is shown below. When I removed the pump from the tank I emptied the remaining fuel from inside its pipe into a very clean cup and indeed similar particles settled at the bottom of the container. Inspecting the fuel filter attached to the pump showed that the “fine gauze” enclosing the contents was intact. The filter seems to contain some black stuff inside and it appears to be leaking into the pump and then on to the injectors. See picture below of my pump. The question I would like to pose is:
1. can the fuel filter be replaced on its own? Replacing the whole pump is costly.
2. Can I add an inline filter between the pump and the injectors? I was advised that the small ones readily available would not handle the pump pressure. The ones I could find are quite large intended for use in Motor vehicles.
Suggestions for a solution are most welcome.
Regards
joe
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It is possible to buy another “strainer” only if you measure dimensions of the old one and use a reputable brand from Amazon as i would not trust china parts on a Hyosung motor that is already annoyed. As you said, the pump is expensive indeed, you will want to remove the strainer very carefully and replace any “retainer” pins holding it in. As long as the strainger port is the same that can slot in to the pump and isn’t too big (will hit metal wall of tank if it is too big or sticking out too much)
Inline fuel filters can burst eventually, so most of them are china made (very very mass produced in china) for many carb bikes that have very low fuel pressure as the carbs have a tap that is like opening the sink a tiny bit. The electric pumps can push 5 bars of pressure sometimes in a motorcycles , that is some difference! (Hence pressure regulators/manager on your fuel pump, as it is instant on/off on ecu demand)
I will further research if it possible to steal OEM filters from cars using electric pumps (ie. small cars) and get OEM versions. Ie, retrofit OEM Toyota filter gauze (since it’s japanese made i am sure) , and clamp it to hyosung pump , i expect the filter to do its job well since car will have big injectors.
We have to be careful also, as if the gauze is too “open” , it will allow small particles to escape and our small bike injectors will not like it, so we need the gauze to be “extra fine” (or have small pores enough to let liquid through but keep any micro particles trapped inside)
It looks like yours is due for service, so it is a good job you took it out!
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Hi Joe,
Thank you for the update. I followed your instructions and checked out my ISC valve. I removed ISC from the airbox and turned ignition “ON”, it unscrewed itself completely and flung the parts because of the spring pressure. I put it all back together and re-installed it.
fyi, According to a Hyosung tech on Facebook, our bikes have one TPS on the ‘front’ throttle body if you look in between the two throttle bodies. It indirectly reads both TBs because the second TB is supposed to be synced to the first TB from factory (bad design but that is how it is). I zeroed out (closed) both the throttle bodies and started the bike (based off of ISC only). It started and idled rough, did not respond well to throttle. Then I bypassed the ISC temporarily, by blocking off the two vacuum tubes, to make the bike idle and respond to throttle based off of throttle body settings only (like it was before I found out the ISC bypass). With the front throttle body closed and rear throttle body slightly open, seems like we’re back in sync (or close to it) the bike idled well and responded to throttle like it should (I should just leave it here and enjoy the riding season, but curiosity is a bitch).
At this point, I lock the TB settings right there and introduce the ISC back into it. The bike starts, revs high for a few seconds and then settles down around 1600 rpm. Now I’m riding it normally, with some occasional sputtering/bogging when taking off from lights. It does not stall, idles well and I am givin’ her the beans.
Next plan is to finalize and fine tune the TB sync using a manometer (using a T-fitting with ISC vac lines) and checking ISC operation on/off throttle (I think my ISC is not responding fast enough when I go on throttle and try to take off).
Hope this helps!
Regarding your question about the fuel filters for our pumps, there are brand new replacements available on Ebay, that can be installed without replacing the pump. Check link below: https://www.ebay.com/itm/161494487889?fits=Make%3AHyosung&itmmeta=01HW3FJGZVNMV5P4P6M7RAW72A&hash=item2599d25351:g:3rUAAOSwDthiIWeq&itmprp=enc%3AAQAJAAAA0BLOBSeT%2BNNUM73lPj14WcgjCK%2BSphXINUci%2Fk8kwybi6TS9DAc%2BFkD8v8%2BjoXn9sNSyUnU7ntfpPPoKuOI7VkPbXzMBH%2BqrtXMQvrMZZ%2B%2Fof7QFWBFu1bnMQ%2BRWKian%2Fj3F6Yi1dQ8fjzg%2Fz32wmAP3HhJovy1fgjsc8r%2BGKtRJ4DR%2Ba%2FD3XAVCjopjY8mshXcGjzEHOcErST2oceAkzllwFcuLDwD65ARkU0dWcAMJ44hJfkuTHMGyMJpZob8Def6H6ljpQkiqW0kP2psfYdE%3D%7Ctkp%3ABk9SR4SQyu_gYw
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Att: Marcel,
I look forward to any info you can get. What disgusts about my strainer is:
1. What is that black stuff inside the strainer? All pictures i have seen indicates that the stuff is whiter than white.
2. The gauze enclosing the whole strainer is quite intact. I dipped the strainer without dismantling it in a glass vessel filled with petrol and the petrol stayed very clear. That is unlike the colour of the petrol drained from the other side. I also dipped the strainer in carb cleaning fluid and liquid turned immediately coffee black.Att: Sam,
Interesting observations. My bike too has just one TPS for the whole system. I will be replicating your settings experiments eventually but at the moment I think it makes more sense for me to resolve the fuel filter issue first.
Thank you for the link you forwarded. The price of $18 for the strainer is not too bad but shipping at $25 is shocking. I am in Europe so I need to find a supplier closer to home to reduce shipping costs.
In the meantime, whilst enquiring about filters at the local carparts suppliers I picked up on of these ( only $1). This obviously will not handle the 5Bar Marcel mentioned earlier but I am considering beefing up the filter housing with fibre glass tape and resin. The filter ends appear to be strong enough to handle the pressure but the cylinder part no. The plan is to wrap Fibre Glass tape several times round the cylinder area.
Is this a daft idea? At $1 it may be worth the trial if I don’t cause damage elsewhere.
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$1 ? – Would you risk it 🤐🤐🤐🤐 Lol. I like you idea of fortifying it. The yellow element inside might be OK for carbs but for EFi systems , it has to be extra fine material as injectors have very small nozzles to make a spray pattern inside throttle bodies. I would be afraid personally to risk that trail lol. 5 bars is a lot of pressure!
Here is a an example of the Toyota Car strainer ;
But , you will need to find a Toyota Strainer in your country with a hole diameter same as Hyosung and also , it should be similar design to Hyosung because the pump sits at the bottom of the tank, you want the strainer to also pick up fuel sitting at the bottom if fuel level is low in your tank.
Sam’s ebay link isn’t too bad , it is similar design to Hyosung (ie. 45 degree pipe with strainer facing down to suck fuel up in to the pump)
I have no idea what the black stuff is inside your fuel strainer is , it could be old particles collected after so many years , i have purchased fuel pumps for customers and i have never seen black things inside from the factory, it is always white fresh.
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Update:
With the throttle bodies balanced with a manometer, the bike is def running healthier. But the sputtering problem after warmup is still there! Today I took the bike for a run on the highway and had to stop at an intersection right after. At idle it sounded like one cylinder kept cutting in and out, jumping from 1600 rpm to 2000 rpm. Light turns green, and it struggles to go, until the rpms rise and it kicks back in and stays like that, until you have to come to a stop again.
Just like before, unplugging the MAP to rear cylinder fixed the idle stumbling/bogging, and I babied it back home. I’m going to pull plugs to identify which cylinder is misfiring, although I’m quite confident its the rear cylinder causing problems. What happens when the MAP is disconnected? Does it dump gas and richen up the mixture? Are these symptoms of a rich condition, or is it leaning out?
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Att Joe:
Have you tried logging your IAP readings while running? Trying to think if we have this in common, does your problem disappear after disconnecting the IAP?
Could you please help me setup a live data reading? My bike has a Daewoo ECU (08K002) and I have the VAG KKL cable. In the back seat, there is a 4-pn connector, but no 2-pin connector as mentioned in other posts.
I appreciate your help!
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Att Joe: Have you tried logging your IAP readings while running? Trying to think if we have this in common, does your problem disappear after disconnecting the IAP? Could you please help me setup a live data reading? My bike has a Daewoo ECU (08K002) and I have the VAG KKL cable. In the back seat, there is a 4-pn connector, but no 2-pin connector as mentioned in other posts. I appreciate your help!
Please let me know how the fuel strainer replacement works out for you. I am going to pull my filter out once I run out of this tank.
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