[mostly_water]

Thanks for the responses, I really really appreciate them.

The problem hasn’t resurfaced yet, statistically, it won’t be more than one week before it acts up again.

I have checked all the grounds I could find, removed every bolt and cleaned every contact with some sandpaper and WD-40, none of the contacts looked bad, but who knows.

Thanks for the chart BeoWolfe, when the problem returns I will check the other relay and troubleshoot with the chart.

I fear that Blake’s suggestion might be the real culprit, either a failing triac in the ECM or some other internal ECM problem. It’s curious how the fuel pump relay clicks so rapidly when the problem is acting up, so rapidly it sounds like a buzzing (10 or 20 times per second). I took the plastic cover off the relay last time, and could see that magnetic clapper slamming back and forth as hard and fast as it could. The sound was really loud. If the ECM controls the relay by grounding it, there is something curious going on there to cause it to trip on and off so rapidly. I will measure the voltage at the relay the next time to see if it is constant, high or low. Hopefully cleaning some grounds have fixed the problem.

I hoped that the unique relay buzzing might have sounded familiar to someone, but this might be an oddly rare problem to solve.



Thanks again everyone.



Todd.