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2.6 Fuel Pump Circuit

PostPosted: Sun May 09, 2021 9:42 pm
by GenOner
Trooper 2.6, this is a weird one for me.

Starts cold, runs a bit then dies. Let it cool overnight and I can repeat.

While starting the starter relay powers the fuel pump
After starting the alternator closes the Engine Relay which closes the Fuel Pump Relay
The Oil Pressure Switch will shunt the power to the FPR to ground if pressure drops or loosing alternator power to relay will do the same.

So it starts, then looses fuel after some period of time, then won't restart. If it was the alternator or oil pressure then it would start then die after releasing key from the start position. I can jump the fuel pump and it will start/run fine.

What the hell is going on here?

Re: 2.6 Fuel Pump Circuit

PostPosted: Mon May 10, 2021 6:51 am
by itsmehb
What your saying is true. At least that's my understanding of the circuit. There's a link in a post somewhere here that describes how to jumper the relay to eliminate the alternator. If it were mine I think I would try that anyway. I've read posts here that other members having similiar problems would take there alternator and have it tested and be told it's good when in fact it isn't. The circuit in the alternator could still be faulty even though the alternator checks good.

Re: 2.6 Fuel Pump Circuit

PostPosted: Mon May 10, 2021 10:30 am
by GenOner
I did use a jumper to bypass, starts and runs fine. But even if the alternator was bad, it would still fire while starting, then die after key goes to the on position. This is what stumps me. Once warm it won't fire. Guess I'll have to test all the wires once it gets into a no-start condition. I was hoping someone had the same experience and could point me straight to the source.