My 89 starts and dies right away and I have done some troubleshooting but im at a standstill. When I jumper FP to Bt it does not stay running. I have 12.08 @Bt with the key on, With key off I get 1.6 ohms from ground to FP, I check the VAF I have continuity between FC and E1 with the vane open, on the connector side I have 12V @Fc with the key on. Do I need to continue with the COR checks? Any thoughts would be helpful.

 

It sounds like you're well on your way! Speaking of sounds, when you jumper Fp to B+, do you hear the pump running? (In my reasonably-quiet garage, I can hear the pump while standing at the diagnostic connector; you might have to get closer to confirm.)

1.6 ohms to ground for the pump is less than half of what I get. https://www.yotatech.com/forums/f116...-quits-312747/ But measurement of resistance that low is notoriously difficult.

 

I can’t hear it run and it is very quiet here. If I had a wire diagram maybe I could check continuity to see if the critters have been chewing wire between the front and back of the truck. I wonder if it runs from for to the pump?

 

You could double check your resistance measurement by checking the current from Fp to B+ (it should be 12v/1.6 ohms, IF your resistance measurement was correct).

My bet is on a bad pump, which means dropping the tank is in your future. (Though, that doesn't explain the starts and dies; a truly dead pump should push no fuel at all.) But once the top of tank is accessible, disconnect the connector and apply 12v there, to rule out the possibility you have a short in the wiring from the engine compartment back. I don't have an EWD for your year, but on the '94 it's a 2-pin connector with Blue to 12v and W-B to ground.

 

Okay thanks for your help

 

wouldn't disconnecting the return from the FPR into a suitable container and then "running" the pump be a better call to verify pump operation rather than dropping the tank and testing?

 

Absolutely. He says he can't hear the pump running with the jumper, so finding that it is actually pumping silently is a long-shot. But a cheap/easy one, so sure.

 

[QUOTE=wallytoo;52491785]wouldn't disconnecting the return from the FPR into a suitable container and then "running" the pump be a better call to verify pump operation rather than dropping the tank and testing?[/QUOTE.

I tried that and no joy so I guess a pump is most likely.

thank you

 

well, if you have to remove the pump, you can at least "bench" test it. if it works, it might point to a wiring problem in your truck.

 

You know, it might be worth pulling the COR and testing the continuity to the pump from there. I don't understand how it would start at all with a completely dead pump. Fp runs from the diagnostic connector to the COR and then onto the pump; if something is messed up between the diagnostic connector and the COR, jumpering Fp to B+ wouldn't do anything. The pinout for the COR socket is in the posting I cited above.

 

Its been a while since I posted on this... I replaced the pump and it works when jumpered Ran for a while and started doing the same thing, troubleshot the COR and replaced it and the truck ran for a while and now doing the same thing Starts and dies Thoughts?