Fuel Pump Pressure Question
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From: Cottage Grove, WI
Fuel Pump Pressure Question
Hey guys, this question pertains to my 89 F250. I know that this vintage truck has 2 fuel pumps, one in the tank, and one mounted on the frame rail. Does anyone know what pressures these pumps pump up to? Ive heard the in-tank pump is just a low pressure feeder pump, but i have not been able to verify this anywhere. Im curious if using just the in-tank pump would work for a carburated engine. Thanks for any help!
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From: Central Mississippi
Try this:
https://www.ford-trucks.com/forums/1...e-reading.html
Don't know if there is a difference between the total pressure of early & later style pumps, but I suspect they are the same. You'd still need an adjustable regulator & return line to get it down to 5-7 lbs.
https://www.ford-trucks.com/forums/1...e-reading.html
Don't know if there is a difference between the total pressure of early & later style pumps, but I suspect they are the same. You'd still need an adjustable regulator & return line to get it down to 5-7 lbs.
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
I remember reading a thread a few years ago and someone said that they disabled the high pressure pump and simply used the in-tank low pressure pump to feed their carbed motor. The pressure was correct.
Just going by what Ford has a pattern of doing, this makes sense. There were several years where Ford made both carbed and EFI motors. If they use one in-tank pump for all trucks, and add the high pressure pump just for the EFI trucks, it saves them a lot of money from a manufacturing standpoint. Once all the trucks were EFI (actually, a couple years later), they moved everything to the single in-tank high pressure pump.
Just going by what Ford has a pattern of doing, this makes sense. There were several years where Ford made both carbed and EFI motors. If they use one in-tank pump for all trucks, and add the high pressure pump just for the EFI trucks, it saves them a lot of money from a manufacturing standpoint. Once all the trucks were EFI (actually, a couple years later), they moved everything to the single in-tank high pressure pump.
Fleet Owner
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From: Easton,Ks
I once took a fuel tank and pump out of a 89 van and put it in my 82 E350 with a Carb 460 engine because I waned more fuel to the engine and it ran in series with the engine mounted mechanical pump. I had no problems running it that way.
I think what Andy said above is what Ford did.
I think what Andy said above is what Ford did.
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On a 88 F350 with a FI 460 the intank pumps do not have any pressure to speak of: I was skunked by them once, I used a fuel pump PSI meter that goes to 15 PSI it registered nothing on the dial. Maybe .5 PSI, when I pulled the hose off the pump was running and pumping fuel on the ground.
The 88 will start and run with the intank pump OFF. I believe they are only there because the early gas tank selecter valve used the slight pressure to swap from one tank to another. I switched to a diesel selection valve so far so good. The frame mounted HP pump runs about 40 PSI ar idle (high vacuum) at full load it runs 46 psi.
I added an in dash electric fuel pressure from glowshift gauges. Cheap and effective gauge.
The 88 will start and run with the intank pump OFF. I believe they are only there because the early gas tank selecter valve used the slight pressure to swap from one tank to another. I switched to a diesel selection valve so far so good. The frame mounted HP pump runs about 40 PSI ar idle (high vacuum) at full load it runs 46 psi.
I added an in dash electric fuel pressure from glowshift gauges. Cheap and effective gauge.
Fleet Owner
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From: Easton,Ks
oleman,
The in-tank pumps have to put out 4-5 PSI to switch the selector valve and into a gauge will have 7-12 PSI.
Sounds like your in-tank pump was dead.
Also the idle fuel pressure with stock parts for a 460 is around 32-34 PSI and WOT around 40 PSI. With the vacuum line removed from the FPR nipple around 40-45 PSI.
The in-tank pumps have to put out 4-5 PSI to switch the selector valve and into a gauge will have 7-12 PSI.
Sounds like your in-tank pump was dead.
Also the idle fuel pressure with stock parts for a 460 is around 32-34 PSI and WOT around 40 PSI. With the vacuum line removed from the FPR nipple around 40-45 PSI.
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Posting Guru
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From: Cottage Grove, WI
Did ford use an in tank pump with the carbed engines? I know they had the block mounted fuel pump, i thought that was it? When i try and look it up at any parts store, the only thing available is the block mounted pumps
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Fleet Owner
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From: Easton,Ks
Sure, all the 1985-1987 460 carbed engines had the pumps in the tank and none on the engine. And some of the 460 back as far as 1982 and maybe before that had them too. All of the 460 engines that had it also had the hot fuel bypass to prevent vapor locking.
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