KTM 500exc engine not starting!

[Mohammad Saad]

Hello Everyone,


We've received a new ktm500 exc engine(2017 model), but are having some trouble starting it. Any kind of help would be appreciated. Thanks in advance.



What's wrong-

1) When we try to start the engine, the starter motor does cranks the engine but the engine does not starts.

2) We checked for spark, and just after pushing the crank button, a spark is seen but only once. After that throughout the crank, spark plug does not provide any spark. Confirmed this many times.

3) According to the wiring diagram, ecu/ voltage regulator should provide ground to power relay, but due to some reason it is not doing so. Anyway, we bypass the power relay and provide power to ecu and other electricals. The fuel pump also turns on for 3 seconds, but after that fuel pump does not works while cranking the engine.


What we've done-

1) Checked the injector.

When we try to crank the engine, it sprays fuel initially, but since the fuel pump is not working, fuel line loses pressure, and it stops spraying.

2) Cranked the engine with/without map and coolant temp sensor.

Some people on the forum had problems with running engine having one of the sensors plugged in, so we tried to run the engine with/without any of them. Sensors are working fine, engine still has the same problem.

3) Rollover sensor is in correct position.

4) Connected the dignostics tool, no fault codes found on ecu.

5) Checked the throttle position sensor, it is calibrated to standard values as in the manual.

6) Checked for the side stand sensor, no problem there.

7) Checked the ignition coil resistance. Resistance found corresponds to standard values.

8)Crank position sensor is working fine, since we were able to read engine rpm while cranking through dignostics port.

[Gautham Ram]

Hello Mohammad

That's a brief explanation about issue you are facing,

My first suggestion to you would be to check your system grounding, if that is good then your relay should clap when you turn on the power. Now that you have by passed the circuit lets eliminate this issue.

The Fuel pump is priming for 3 secs and spark glows once and no more this rings bell for safety system, Check your roll over sensor and side stand position sensor, I believe you have either short circuited these two sensors or have installed the sensors.

If you have Short circuited any of them I suggest you install the sensors because the system might check rationality.

In case if you have installed the two sensors as such, check for various positions of sensor as in change angle or on and off.

Another last shot I would give you is to try firing the engine by removing all sensors other than Crankshaft position sensor.

Also There is a very slight chance of ECU malfunction, please check that too if you have not


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Gautham Ram

Fuel Systems Calibration Engineer at Royal Enfield
Former Tech Lead at Camber Racing