This is in a jeep with a Painless harness but it is an 87 camaro 5.7. When cold fp will prime and run while cranking motor starts and has good fuel pressure. When the engine is warm the fp will not prime nor run while cranking. Motor will start amd the oil pressure switch will take over. I suspect the computer is not signalling the fp relay but have not yet verified that. Any idea what would cause this?

 

Have you tried swapping out the relay? Or put a test light on it, to see if the ECM is indeed commanding it on?

 

You should get enough oil pressure when cranking to have the oil pressure switch supply power to the fuel pump? Are you sure the switch is okay?

 

I have not been able to duplicate the issue so my assumption is the contacts in the relay are failing. Had this happen with the electric fan yesterday, would work then quit then work again, it finally gave up. Relay would pick up but the contacts were toast.

Motor has always ran fine once started and after experiencing this problem I thought that might have been part of my hard hot start issue. Put a high current push button in to bypass the relay for starting and I still have the hard hot start issue so that was not it.

Anyway going to change the relay and hope for the best. I have two different bypasses, manual and oil pressure so at least that will never leave me stranded.