not holding fuel pressure

[jr32560]

87 F150 been sitting a few years
new frame rail pump new rear pump
was running now not
loosing fuel pressure
goes to 40 and drops off fast
swapped the fuel reserve for another does the same thing "used one that is"
clamped the return line and jumpered the wire to fuel pumps raised to 100 psi
gonna try the pressure regulator-
anymore ideas?

 

[jr32560]

well wasn't the regulator
think the new frame rail pump is crapping out
back check valve seems to be leaking down

 

[5Rangers]

The 87 doesn't have a check valve, it has a dual function reservoir. I would think your in tank pump isn't doing its job. You can pull the pressure line off the reservoir, grd the test plug turn the key on to activate, make sure the in tank is pumping, (into a bucket) if not, check power and grd. Make sure the lines are clear, filter changed with a new one. Make sure you have good power and ground at the in tank and the frame rail pumps. Let us know what you find.

 

[jr32560]

found that the new fuel pump on the frame rail was defective
seems a built in back check valve was at fault
new doesn't always mean good I guess~~~

 

[F150]

Yeah, it happens sometimes.

 

[Fellro]

Never is a guarantee, there are occasional failures right off the shelf.

 

[Beach66Bum]

I had fuel pressure loss on a EFI truck and it turned out to be the o-ring for the fuel pressure regulator got pinched and wasn't sealing. Would lose pressure after a hour. Glad you found the problem.

 

[5Rangers]

Well, I learned something here, I didn't know that frame rail pump had a check valve.

 

[jr32560]

Well, I learned something here, I didn't know that frame rail pump had a check valve.

yupper built into the outlet side
won't let the fuel pressure go back in the reverse direction
didn't know myself till I did disassembly of the old pump
and the new one worked for about 20 minutes then wouldn't hold pressure
was a head scratcher for sure

 

[dustybumpers]

So ya got it running Jr?

 

[jr32560]

So ya got it running Jr?

had to or haul it to the scrap yard
still fighting other issues though may be on road soon
I hope-- will be sure to keep the daughter out of it