2004 vulcan 750 shuts off

Intermittent faults are difficult to locate and occasionally the cause is never found. Often the problem cures itself or somebody cures it by desperate and mindless fiddling but doesn't know how.

I tell my customers to persevere and eventually a pattern will emerge - the same corner, the same stretch of road, the same sort of weather, the same speed, the same gear, etc.. Once a pattern is recognised it increases the chances the problem can be repeated predictably or some serious detective work might provide further clues.

Fitting temporary telltale lights to monitor supplies and grounds around the circuit can be helpful.

I have had two cars where the intermittent fault was inside the ECU. Very difficult to prove and too expensive to replace without justification. On one car I was lucky and had a timing light connected when the fault happened. I watched the timing mark move and keep moving until it was almost out of sight and the engine stopped. It restarted immediately and ran normally until the next time.