FI light and turning engine off while driving
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Bike Model = : Hyosung GT250i: 2011:
My Hyosung GT250i (29,100 km; 2011) is experiencing the following problems:
1. While riding in 4th or 5th gear, the red FI light occasionally comes on for a few seconds up to 20 minutes, without any noticeable changes in handling. It eventually goes out on its own, but it always goes out when I slow down and shift down a gear. It never comes on when the bike is stationary (idling), so it’s impossible to run a diagnostic check while the bike is stopped. This has been happening for years, but it doesn’t affect the bike’s performance.
2. Since this summer, the engine stalls while riding. This happens unpredictably and lasts only briefly. You can restart it while coasting. No error is indicated by the FI light during this time. Idling is very unstable. The RPM fluctuates, and the engine stalls after a short time. It gets worse when the engine is warm.
What could be causing this, and how can these issues be fixed? Do they have the same cause, or are they caused by different issues? As for electrical problems, i’ve previously had a faulty speed sensor, the rear ignition coil, and the headlight relay.
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These issues point to a possible of the following:
- Harness needs all connectors check for oxidization of the pins
- Check ECU for oxidization pins  (you can use contact cleaner on the harness) but never put liquids at the ECU itself, just blow the ECU pins with compressed air and let it dry fully on the harness before pluging stuff back in.
- Spray carb cleaner on on the throttle bodies to see if there is air leaks , the bodies have little o-rings that may have age-rotted ?
- ISCV (idle speed control) – Common but does affect idling and gear changes (momentary idle for rider to change gears ot twist throttle again)
- TPS Sensor  (use service manual to make sure its in spec, its on the forum as 250 EFi manual)
- Fuel Pump is waning (age) or strainer-mesh is clogged in up (triggers Fi when riding) ,
- If the LCD glass panel says 50mph / FI / 20mph / FI  0 / FI / while moving, its 100% to do with the pump and injectors.
- get Wynn’s Formula Gold Petrol (or extreme equivalent)Â (not RED-EX) , pour the whole bottle in the tank with maybe 3 bars of fuel , rider until its nearly empty , you want these bottles to make their way down the whole fuel system to clean any stubborn accumulated deposits
- Injectors waning (age?)
- Check rtelay for fuel pump and replace it  (or if the pump uses a 30A fuse , check it ) == It is up to Hyosung to use a 30A fuse or 20A/40A relays on these bikes for fuel pumps, they updated the harness a lot across all EFi machines.
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Do i have to synchronize the throttle valves?
I would not touch the butterfly valves if they are still original (nobody touched them before you), as it could be hard to re-balance it if you’re not sure what to do. Normally the factory sets up and discourages anyone from touching them.  If in doubt , have a spare back up throttle bodies from a crashed donor bike, just to rule things out.
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I’ve now separated the airbox from the throttle body. One of the rubber connecting sleeves had a tear of 2–3 centimetres along the edge. It was starting to crumble. I’ve ordered new ones, but they won’t be delivered for another 10 days. I cleaned the connector pins, even though they all still looked new and in good condition. I didn’t dare touch the ECU connector, though. I also cleaned the ISC solenoid. Some black gunk came off, but it didn’t seem that bad to me. I can now access the throttle body. What work should I do on it? I have plenty of time before the rubber parts from Korea arrive.
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While the airbox is apart, split the throttle bodies carefully and inspect the O-rings, there is 4x of them (middle x2) and 2x to the engine cylinder heads
Then when the throttle bodies are apart , use carb cleaner all over them  (remove sensors first!)
Least you want to make sure the intake system is pristine so there is no macro air leaks , making the idle Speed controller work too hard or throttle possibly getting sticition (or jammed from dirt)
For sensors, their connectors (wires) and the sensor pins should be cleaned with contact cleaner and dried up for 24hrs at least if its cold out doors.  Now use this time to check the pins for oxidization , as too much oxidization can affect how precise the sensors can send signals back to the ECU. A badly corroded pin can easily jump from factory 0.5 ohm to 3 ohms, that’s enough to panic the ECU, it’s just an example.
Remove the ET sensor carefully (Temp Sensor in front cylinder) ,  the pins will need to be cleaned. If the ECU asks the sensor what temp engine is, and it gets 50 ohms (100 degrees celcius) , it might go haywire when the engine is actually 65 degrees , it was the oxidized pins and connector plug fouling the ECU with incorrect values. (these values are just examples, real figures will be in the service manual)
The service manual will tell you if the sensor is good or not with a meter to test and you use a hot glass with thermometer. If the glass bowl of water says 60 degrees , you need help with someone holding the sensor TIP in to the water (black body must not touch water) , you will probe the 2pins , it should say  (example) 2,000 ohms , the manual says 65-70c should be 3,000 ohms etc, you will know if you want to clean the sensor or replace it if it is failing.  The ECU does depend on temp sensors.
Also your airbox will have a TEMP sensor (Air Temperature) as hotter air has less oxygen, so it will tell the ECU how much fuel goes to the injectors, so the engine doesnt get too rich or too lean.   Another “temp sensor or heater element” is the lambda sensor (hot exhaust gases , it will warm it up) but not every modern bike uses this , so we just call it Oxygen Sensor instead, it will sense oxygen in the pipes (too rich or too lean)
All these separate parts affect how well the bike idle, runs , and rides. So do one thing at a time and the manual will help you test each part to see if they are still in spec.
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Today I ordered O-rings for the sealing surfaces and started removing the throttle body and the fuel injection unit. What I just can’t seem to do is disconnect the throttle position sensor connector. How the heck do you do that? Where’s the latch mechanism I need to release? It’s the sensor with just one screw.
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One of the two rubber connectors between the airbox and the throttle body is damaged and needs replacing. I’ve ordered and paid for them, but it seems I’ve fallen for a fraudulent website. The rubber connectors are no longer manufactured and are sold out everywhere. If anyone knows where to get hold of them, I’d be very interested On the other hand, there might be a way to replace them with parts from other manufacturers. Perhaps someone will have an idea after looking at the sketch with the approximate dimensions (in millimeters) and the photo. Someone on eBay is offering 5 pieces, but won’t ship them to Germany. It seems to be the last offer available worldwide.
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I sell them below
https://www.ebay.co.uk/itm/257243814986
They come as SHORT HEIGHT (from carb model) or Tall Cone style = Makes no difference to EFi ,  if ebay won’t let you ship them (I always enable global shipping) it is up to ebay if they themselves will ship to you as we use PitneyBowes (ebay owned couriers for global orders)
Otherwise, send an email for a custom quote and we will use the UK Postoffice to your local country post likely DeutschePost
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Since I was unable to find replacements for the damaged rubber fittings, I reassembled the machine using the old ones. I cleaned the throttle bodies and the ISC sensor, replaced the fuel injection unit and the air filter, disconnected all electrical connectors, cleaned them, and sprayed them with contact cleaner; I removed the fuel pump and cleaned its filter; and I calibrated the regulator and the IAP sensors. There was no corrosion or significant dirt anywhere. Except for the throttle body connectors to the airbox, all parts were intact and looked good.
The bike starts up, but after a few fluctuations, it quickly stalls again while idling. Above 4,500 rpm, it revs willingly, smoothly, and responds to the throttle. Below 4,000 rpm, it shows slight jerking and sluggishness. It responds sluggishly and with a slight delay to twists of the throttle grip and sounds weak. I didn’t ride it, since the reassembly was only temporary.
What’s new is that it now displays error code C41 after stalling. The fuel pump is making operational noises; I replaced the fuel pump relay: no change. Today I’m going to try cleaning the injectors with EFI cleaner added to the gas. I’m not holding out much hope, but what else can I do?
As I’ve been asking around, I’ve now been told that every component and every sensor could be the cause of the problem. Many of these are very hard to find as replacement parts—for example, the ECU or the rubber fittings I mentioned earlier, but also some sensors.
The motorcycle is starting to feel more and more like a “disposable motorcycle” to me. It runs fine at first, but as soon as more complicated problems arise, you might as well just get rid of it. There are no replacement parts, and the mechanical work between the cylinders is impossible without custom-made tools—and it’s a real pain. You don’t see this motorcycle around anymore, and I haven’t seen its popular sister model, the GV250i, in a long time either. I haven’t met anyone who’s said, “I had that problem once, and this is how I fixed it.” People don’t repair them; at best, they strip them for parts or send them to the scrapyard. And I’m slowly starting to consider doing the same.
<i>Translated with DeepL.com (free version)</i>
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Since I was unable to find replacements for the damaged rubber fittings, I reassembled the machine using the old ones. I cleaned the throttle bodies and the ISC sensor, replaced the fuel injection unit and the air filter, disconnected all electrical connectors, cleaned them, and sprayed them with contact cleaner; I removed the fuel pump and cleaned its filter; and I calibrated the regulator and the IAP sensors. There was no corrosion or significant dirt anywhere. Except for the throttle body connectors to the airbox, all parts were intact and looked good.
The engine starts up, but after a few fluctuations, it quickly stalls again while idling. Above 4,500 rpm, it revs willingly, smoothly, and responds to the throttle. Below 4,000 rpm, it shows slight jerking and sluggishness. It responds sluggishly and with a slight delay to twists of the throttle grip and sounds weak. I didn’t ride it, since the reassembly was only temporary.
What’s new is that it now displays error code C41 after stalling. The fuel pump is making operational noises; I replaced the fuel pump relay: no change. Today I’m going to try cleaning the injectors with EFI cleaner added to the gas. I’m not holding out much hope, but what else can I do?
As I’ve been asking around, I’ve now been told that every component and every sensor could be the cause of the problem. Many of these are very hard to find as replacement parts—for example, the ECU or the rubber fittings I mentioned earlier, but also some sensors.
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Now it won’t start at all and alternates between displaying C41 and C25. I replaced the rear ignition coil and the C25 error has gone. But it still won’t start. Now it’s showing C41 again. Today I wanted to remove the injectors, but there are those pesky connectors again. How do you unscrew them?
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Usually the grey slider stays inside the connector and you press down to pull the plug out of the injector, though again like other connectors they need a careful approach so we don’t break the tabs (it is a good thing so they don’t vibrate out immediately when riding)
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My GT650R 2013 has the FI light and on the triple key it flashes 10-1-3-8. I only just worked out how to message. Can I plz get a little assistance to sort out the issue. Please, thank you and TA?
This topic was for the GT250 , you could start a new topic if you’re stuck but before you do that , go to the forum first and get the 650cc manuals we posted for download, I uploaded every 650 manual i could find, they usually explain the error codes for you.
Regards
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