Quote:
Originally Posted by sfran
Please help me sort this out. I need my truck this weekend!
So my truck has been acting funny lately and finally wouldn't start the other night. I crawled under and banged on the tank, and presto, the pump came on and it started up while still running not that great. So obviously I assume fuel pump. This is my 4th fuel pump I've done in the 10 years I've owned the truck, now after replacing it this time, the damn thing won't start. I have never had an issue after replacing one before but this one is driving me nuts.
I have checked everything I can think of. I have spark, 11.2 volts (with a weakish battery from cranking, now charging) at the connector on the pump in the tank, I have a good ground, I have tried 2 new pumps, and a new sending unit to compare voltage and pump operation, but can't drop the sending unit in the tank, because then I will have to buy it. I know the pump is kicking on, but it is very quiet. I put a fuel pressure sensor on the fuel rail and I can only get it up to 15-18 psi.
What am I missing, or where should I turn next? My Napa guy said it might be the ignition module. I think this is the one with the heat sink?
I don't want to just throw parts at it so any help would be appreciated.
Thanks
****Update*** just thought to put starter fluid in throttle body, well actually carb cleaner cause its all I have. And voila, it started. So I am assuming I am the unlucky bastard that gets two bad pumps on the same day? Has to be fuel right?
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If it runs after being cranked with an accellerant, how would that lead you to conclude low fuel pressure was the problem? Would it not still have low pressure and therefore why would it run?
These TBI engines, I learned from ChevyTech and others, need to get above like 400 RPM before the ignition module starts sending the "run" mode to the ECM. I had the same experience several years ago. In my case starting fluid would crank it, and it would idle and run fine till you shut it down, then same problem again, till I would give it another dose of starting fluid. But altho the engine would operate fine, the transmission would not shift correctly, another of our ace techs suggested trying a TPS, which I did, it solved both the "no crank" and the shifting issue, and the truck has been doing fine for 3 or 4 years now. That is why I suggested the TPS, I know from experience that a malfunctioning TPS can cause issues you'd never expect. Not sure about your year model, but don't these trucks only require something like 9-13 PSI in the first place? Like ChevyTech said recently, hard to diagnose something you can't see, hear, feel, smell, just trying to help you out.