Reply To: Non-start (no fuel pump prime)-new owner – 2018 Gt650r
That’s a multi-issue there hmm, lets try to address the pump.
If the ECU senses the bike isn’t good or if the ECU is toast = The pump won’t prime.
The ECU directly controls the pump, so maybe we either have a burst fuel pump relay and fuse
(On some 2018 models = the pump has its own “Relay” and its own “fuse” = So 2 things here just for the pump)
Headlights = Relay may be burst ? Without the relay, the lights stay OFF unless bulbs have gone burst at the front, the rear is all LED, so should just light up.
Also LEFT switch gear & Right Switch gear = Directly control the lights too, so if either of them are faulty or have issues with contacts , the lights stay off.
You will want to replace all the fuses (If its 15A , use 15A and some fuses are 20A , 30A etc. So match them accordingly as you would not want a 40A fuse on a 30A slot
You will also want to replace all the relays.
As for the pump = Double check the stand, bypass again , verify the same wires at the ECU are complete, so the ECU can sense it. (On carb bikes = If the clutch switch or stand switch are dead, the CDI would cut the sparks off, so principal is the same for EFi models)
Buy a backup ECU just incase, it would make troubleshooting much easier too.
Test the stator using this topic and verify , confirm the readings?
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
ECU won’t tell if the coils are dead or not, so use that same link to check your coils and confirm their readings? = if the pump primes back to life but there is no sparks , the ECU may get shot , we don’t know if they got water damaged , as you said you found places of mud and water ingress on the electrics.
While you can, disconnect everything on the bike, and try to test every sensor with a meter ? = Tedious process but helps narrow everything down.
Browse this forum and get the latest service manual , they have picture tutorials on how to test each sensor.
Since the sensors are out of the bike, this is a good time to remove the harness and clean every connector with Contact Cleaner. All Hyosung 650 ECU’s for whatever reason are more sensitive to resistance changes in the wires (oxidization etc…) unlike carb models. Hence Hyosung Korea tried to replace most plugs with waterproof japanese connectors. but it still can’t hurt to double check.
Hope this helps and keep us posted!