Fuel pressuere drop - which fuel pump??
#1
Fuel pressuere drop - which fuel pump??
I have a fuel pressure problem in my '86 F150, 5.0L EFI engine - pressure was dropping like a ROCK when the throttle/load was applied - at idle pressure was good ~28 psi and vacuum off the regulator it was ~44 psi but as soon as the throttle was pressed the pressure dropped! I can't believe the thing ran as good as it did with such little pressure! Hopefully it'll help my gas mileage - I've been getting ~10.5 mpg lately!
The only nagging question is that the pump provided enough pressure at idle and under no/light load, but it just couldn't handle the volume required with the engine under a load - so would that be the in-tank pump or the high pressure pump??? Any opinions on this one? I really need to know since the in-tank pumps are $38 and the frame mounted ones are $80. and I don't want to just buy all 3 for a shotgun repair approach.
Thanks in advance for any info!
The only nagging question is that the pump provided enough pressure at idle and under no/light load, but it just couldn't handle the volume required with the engine under a load - so would that be the in-tank pump or the high pressure pump??? Any opinions on this one? I really need to know since the in-tank pumps are $38 and the frame mounted ones are $80. and I don't want to just buy all 3 for a shotgun repair approach.
Thanks in advance for any info!
#3
#5
Well long story short - the culprit - the filter in the selector valve - didn't even know that it was down there - I've replaced the frame mounted fuel filter and checked everything for obstructions, etc. Got the hint from the local dealer that said just to toss the filter as he's seen lots of them plug and cause problems - well, I purchased a replacement (if it's plugging with crap it's got to be doing it's job!) - no wonder why the in-line filter looked perfect - it's getting filtered fuel. Anyhow - now I can run foot to the floor all the way to 70 MPH without bucking or backfire and that's good enough for me!
I want to thank everyone for their help! Didn't have to waste too much $$ fixing it and in the end it was a volume probelm getting to the high pressure pump - just not where I thought it would be!
I want to thank everyone for their help! Didn't have to waste too much $$ fixing it and in the end it was a volume probelm getting to the high pressure pump - just not where I thought it would be!