I was driving home and truck lost rpm's stalled and barely rolled into a parking space.

1994 X-cab 4x4 3vze

I thought it was the fuel pump, removed bed and started testing

Pump will not run while cranking
jumped b+ - Fp with ING on and pump runs
12V to Fp, pump runs
b+ reads 12v
tank is clean and strainer is clear (i can see through the gas to the bottom and its clear)
pump was replaced 4 months ago
fuel goes into cold start valve and rails for injectors (loosened bolts fuel squirted out)
blew fuel lines back with compressor and replaced fuel filter

thinking its an electrical problem i tested EFI fuses, 12V both sides
ING 7.5 fuse okay
replaced EFI relay and COR relay

still no power to the fuel pump when cranking and no fuel goes into fuel pressure regulator if pump is powered with bypass

electrical issue? vacuum issue? fuel pressure issue?

I have been with out transportation for a week, pulling my hair out, help please.

 

Are you 100% sure you are getting spark?

 

Can you smell fuel while it's cranking? Give it a shot of starting fluid and see what happens.

 

sounds like a bad fuel pump relay

 

occasionally it will start for 2 to 3 seconds then stall, so its sparking, seems to be the fuel pressure issue.

tested blue wire to pump, its 9v, but when the key is turned to off it surges to 11v, could this fry fuel pumps?

pump only runs when 12v applied, but seems to be low pressure.

at this point i think its the pump, not sure about the surge though.

 

occasionally it will start for 2 to 3 seconds then stall, so its sparking, seems to be the fuel pressure issue.

tested blue wire to pump, its 9v, but when the key is turned to off it surges to 11v, could this fry fuel pumps?

pump only runs when 12v applied, but seems to be low pressure.

at this point i think its the pump, not sure about the surge though.

 

have you check fuel pressure with a tester

 

it should be 38-44psi if you have check lines and filter what about the pressure regulator/ then there's the bad plan but will do in a pinch most auto parts stores sell a helper in line fuel pump 4 around 30 buck just add to mid line and ground to frame and 1 hot wire and it moves fuel will do for a while

 

I am real sure the fuel pump is not making enough pressure because it doesn't blow the unsecured fuel return line off while cranking. could the low pressure issue be caused by only 9v going to the pump?

 

Well it's not helping.

The other week my truck died and it was a bad connection on the pump (splicing from the P/O). I cut out some wire that was about 1/2 the size it should be and I noticed a difference at WOT, she has more getup and go now so I was not getting the full 12V to the pump.

 

Well, I called the parts store i got the fuel pump from an found out it is still under warranty, walked down their, took free new pump home, installed it, and vroom! it freaking started.......

pump failed
AIRTEX
tank had been drained and wiped out with solvent before the last pump