Question Stancor problems

[BIG JOE]

Well, my fuel pump on the frame rail is not working. I checked the voltage at the fuel pump plug (about 12" prior to the fuel pump and it is getting 12V with key on and 14V with engine running). Is it common to have fuel pumps quit? Where is the best/cheapest place to get a replacement pump?

Drew

It's not common for the 7.3 fuel pumps to out.. but they Do, occasionally fail.

But Try this first ? :

Crawl under the truck, have someone turn the key on, but don't crank the engine. The pump should run/cycle, then stop.. as the fuel pressure bleeds off.. if the pump cycles again.. it's Not the pump.... YET.

Sans having a Good scanner: On the back, right of the fuel filter canister.. is an un-used, plugged, port. from there, you can manualy check the fuel pressure. With a fresh/clean fuel filter, you should have.. +/- 50 psi. If it's less than that.. the Filter is dirty.. or the pump IS going bad (weak).

Ford, IH, NAPA has the fuel pumps.. any others are prolly Remans. (You git what you Pay For ????)

 

[airdrew99]

It's not common for the 7.3 fuel pumps to out.. but they Do, occasionally fail.

But Try this first ? :

Crawl under the truck, have someone turn the key on, but don't crank the engine. The pump should run/cycle, then stop.. as the fuel pressure bleeds off.. if the pump cycles again.. it's Not the pump.... YET.

Sans having a Good scanner: On the back, right of the fuel filter canister.. is an un-used, plugged, port. from there, you can manualy check the fuel pressure. With a fresh/clean fuel filter, you should have.. +/- 50 psi. If it's less than that.. the Filter is dirty.. or the pump IS going bad (weak).

Ford, IH, NAPA has the fuel pumps.. any others are prolly Remans. (You git what you Pay For ????)

Big Joe,
I just laid under the truck with my wife in the seat to turn the key on. With the neighborhood quiet, I could barely hear any noise at all when the key was turned on and my head was about 12" from the pump. Also, I put my hand on the pump. I'm not sure if it is just fuel passing through the pump that is making the noise or if the pump is just barely running. The pump is getting 12V. Is it possible for the engine to even start with this fuel pump not running? I've been driving it for a week since I had the truck die on me. I'm pretty sure my problem last week was the fuel pump. Can these pumps be disassembled?

Drew

 

[BIG JOE]

Big Joe,
I just laid under the truck with my wife in the seat to turn the key on. With the neighborhood quiet, I could barely hear any noise at all when the key was turned on and my head was about 12" from the pump. Also, I put my hand on the pump. I'm not sure if it is just fuel passing through the pump that is making the noise or if the pump is just barely running. The pump is getting 12V. Is it possible for the engine to even start with this fuel pump not running? I've been driving it for a week since I had the truck die on me. I'm pretty sure my problem last week was the fuel pump. Can these pumps be disassembled?

Drew

All righty then.. The pump should, being near it, make a noticable buzzing sound. If you can [Barley] hear it.. it could be on it's way (weak) out.

If the pump was NOT working at all.. the truck won't start. Weak ? Probably/Maybe.

Have you checked yer fuel filter [recently], after this happened ? Clean ?

Just a SWAG but.. I don't think the pumps are servicable/rebuildable, at the consumer level

 

[iracemine]

yeah I can hear my pump from inside the cab. Sounds like its going out. Id say even if the filter or tank filter is clogged it will make some noise. After you change it out you might want to pay attention to the fuel pressures to see if that was maybe why this one went out.

 

[airdrew99]

Well, right before I removed the fuel pump I checked the fuel pressure. With key on engine off I showed 60psi and 60psi with engine running at the fuel bowl (aft plug). As soon as I shut the truck off, the pressure dropped rapidly to zero. I removed the pump and looked it over, then reinstalled it. The fuel pump is extremely quiet, but seems to be operating fine. I then restarted the truck, let it run for about 60 seconds (reading 60psi), then shut it off. This time the pressure dropped to 40 psi within a few seconds, but then stayed there for at least 5 minutes. Am I losing fuel pressure after I shut off my truck? If so, what is the fix? I plugged the new fuel pump in and it showed 60psi and was pretty quiet also.

Drew

 

[BIG JOE]

Well, right before I removed the fuel pump I checked the fuel pressure. With key on engine off I showed 60psi and 60psi with engine running at the fuel bowl (aft plug). As soon as I shut the truck off, the pressure dropped rapidly to zero. I removed the pump and looked it over, then reinstalled it. The fuel pump is extremely quiet, but seems to be operating fine. I then restarted the truck, let it run for about 60 seconds (reading 60psi), then shut it off. This time the pressure dropped to 40 psi within a few seconds, but then stayed there for at least 5 minutes. Am I losing fuel pressure after I shut off my truck? If so, what is the fix? I plugged the new fuel pump in and it showed 60psi and was pretty quiet also.

Drew

It's normal for the fuel pressure to go to 0 when you shut the engine down.

60 psi is good enough for stock Ford specs.

The fact that it held 40 psi for 5 minutes puzzles me however. You might wana clean the filter bowl Real good. Kinda sounds like there could be some junk blocking the Fuel Pressure Regulator orifice at times.. leading to inconsistent flow rate, psi and pump issues.

 

[dpantazis]

Or the fuel pressure regulator spring is relaxed and worn out.

Remember that the FPR is at the end of the fuel system and creates fuel pressure by creating back pressure.

Kind of like a restrictor plate

So if there is gunge holding the poppet open or the spring is bad, you get less pressure.

Sent from my DROID BIONIC using Tapatalk

 

[BIG JOE]

Or the fuel pressure regulator spring is relaxed and worn out.

Remember that the FPR is at the end of the fuel system and creates fuel pressure by creating back pressure.

Kind of like a restrictor plate

So if there is gunge holding the poppet open or the spring is bad, you get less pressure.

Sent from my DROID BIONIC using Tapatalk

That next

 

[airdrew99]

Big Joe and dpantazis,
Where is the fuel pressure regulator (FPR) located? I plan on cleaning the fuel bowl after class tomorrow. I've been thinking about doing the mod to the FPR where I install a few #4 SS washers under the brass sleeve. Do you guys recommend this? Does this affect fuel mileage at all? Does this hurt anything at all bringing fuel pressure up to 70psi?

Last night I removed a small plug with a 4.5mm allen wrench on the driver's side aft fuel filter bowl. Is this where I can see the adjustments made after I put washers under the brass sleeve, or is this spot "upstream" of the adjustment?

Drew

 

[dpantazis]

that assembly you tool apart is the Fuel Pressure Regulator. look at the wiki page on FPR shimming.

this cap and valve spring is the last place in the fuel system before the return line the tank.

be careful with the housing cap, its pot metal and can break very easily. IH and FMC only sell it as a complete assembly. $$$ one of the vendors sells an aftermarket one reasonably.

the fuel pump runs 100% of the time. if there was no FPR, you would get very little pressure but a lot of flow through the system.

the rubber orings are square cut, not round. they tend to fall apart after being in there for a while.