2001 5.7 Fuel pump mod tech question

[whateverz]

Setup:
I bypassed the modules internal bypass (type of prv that circulates it back in the pump)and hardline the pump directly out of the module and are completely relying on the return line to relieve unwanted back pressure on the pump. Is this a bad idea? Is it going to be hard on the FPR or pump? That internal module bypass (prv) would not let it build psi. Basically, the corragated line in the module is hooked directly to the pump, bypassing the modules own cheesy type of prv (that doesnt work). So the extra pressure is using the return fuel line instead. Hope this is clear, if you have taken a module apart you know what im saying.

Question:
I haven seen a OEM module, this is a airtex so I dont know if its just their design. With the airtex the fuel was never in the return line, so im wondering if the oem was setup more like this. It started better and ran better than it did with brand new airtex's, but Im just wondering if this is going to kill the pump/fpr?


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If you want more history on subject read below.
Left me stranded sat night and after a long PITA process this is the jist.

The second POS airtex fuel pump went. I knew thats what it was before I rolled to a stop as it started making more noise recently. I don't believe in paying for the whole module, (such a racket) so I matched up a Delphi FE0114 pump that was in stock at the parts store and a new filter. No start. Got a pressure tester, 0 psi. Unhooked filter and it would just piss a little out, even cranking it would only dribble. Blew from tank to filter, good. Filter, and filter to rail test port, all clear. Made noise like it was working fine. So I tested relay, good. Power at module terminal, good. Pump terminal inside module, good. WTF! So I hardline the pump and dangled it in the tank, started right up! So I took the module apart for the 8th time (think I have a gold metal time with this), and started blowing through module ports and found the internal bypass and noticed it was missing its little grommet to the lower return. So I went back to where it broke and found it (dropped it working in the dark). Put it all back together super tight and siked to get going.....no start!

[j cAT]

your posting is quite weird.


a 2001 does not use a 5.7L engine.

your using an airtex pump instead of the delphi pump as all recommend.

you buy the whole pump assy because these have issues with the whole OEM assy after 10 years. electrical connections/sender/suction leaks.

when the pump is replaced the relay and filter should be replaced.

the fuel pump regulator should be checked with the pressure testing proceedure for whatever engine your vehicles has after any repair to ensure this has the correct pressure and no other fuel system failures like injectors or regulator or leaks.

the return line is used so that the injectors get the correct operating pressure. you plug up the return line the pressure will not be correct.

[whateverz]

Originally Posted by j cAT

your posting is quite weird.


a 2001 does not use a 5.7L engine.

your using an airtex pump instead of the delphi pump as all recommend.

you buy the whole pump assy because these have issues with the whole OEM assy after 10 years. electrical connections/sender/suction leaks.

when the pump is replaced the relay and filter should be replaced.

the fuel pump regulator should be checked with the pressure testing proceedure for whatever engine your vehicles has after any repair to ensure this has the correct pressure and no other fuel system failures like injectors or regulator or leaks.

the return line is used so that the injectors get the correct operating pressure. you plug up the return line the pressure will not be correct.

Sorry didnt know, I just posted in this section cause i thought it would be the same pump, and seems to be more activity here than the Express section. It is a 2001 Express 3500 cutaway 5.7 box van. Moderator please move it if you want.

I got it with an airtex and it was wired for one so i just put another one in 8 months ago for $50, Yes, I know now.. i wont ever buy one again. Thats why I replaced with a Delphi FE0114 Same specs as OEM: 32.4 gph and 61 psi.

It was a bypass or pressure relief leak more than a suction problem, but yes I see why a new module is a better bet. Being that I just spent 100 on the delphi pump if it works this way I dont really want to go throwing more money at it. I will admit to being a cheap azz too.

I tested the relay it was over 80 Omh... I think, Heard 70+ is ok?
Also replaced filter as well

It is at 60-61 psi key on and held 56-58 idling (in spec). Left it for 30mins+ to check FPR and it held. Would of left it longer but I was in the blazing sun on an empty lot and want to get going. FPR could be leaking down, how long is the recommended time?

Return is not plugged, its actually constantly returning fuel from the rail now instead of the pressure bleeding off in the module, know what i mean? Thats what Im worried about, the regulator always relieving that pressure through the rail instead of in the module.

Sorry if im not explaining it well enough. And post was confusing, bastardized and chopped up because I copied and pasted from another post to make it more to the point....failed.

I know the best thing to do is throw a brand new AC delco/delphi module in, but cant really afford that right now. And it starts and runs better than it ever did now. So if it works this way, I want to run it.

[j cAT]

I KNEW this was wierd.

so with this express 2001 5.7L engine it is quite different than a silverado/tahoe/suburban vehicle in many ways.

the pressures your getting are good. 60-66psi. pressure holds key on engine off. this would mean no leaks/leak down issues.

the relay should be replaced because the contacts not the coil go bad and develop pits that do increase resistance to the fuel pump DC motor. since DC is always flowing in one direction you get bigger pits and holes in the contacts which is not good for the pump motor running on a lower voltage.

another airtex failure story ..well I guess they still make crap !

keep the fuel above 1/4 tank at all times. hot weather and low fuel ALL these pumps burn out fast .

running the pressure should be about 57 psi area.

good luck with it. make sure the wire splices are secure and sealed[no water] . make sure the frame rail grounds are clean ed and secure next to the tank.

[whateverz]

Originally Posted by j cAT

I KNEW this was wierd.

so with this express 2001 5.7L engine it is quite different than a silverado/tahoe/suburban vehicle in many ways.

the pressures your getting are good. 60-66psi. pressure holds key on engine off. this would mean no leaks/leak down issues.

the relay should be replaced because the contacts not the coil go bad and develop pits that do increase resistance to the fuel pump DC motor. since DC is always flowing in one direction you get bigger pits and holes in the contacts which is not good for the pump motor running on a lower voltage.

another airtex failure story ..well I guess they still make crap !

keep the fuel above 1/4 tank at all times. hot weather and low fuel ALL these pumps burn out fast .

running the pressure should be about 57 psi area.

good luck with it. make sure the wire splices are secure and sealed[no water] . make sure the frame rail grounds are clean ed and secure next to the tank.

Then I will definitely replace the relay.

With a 55gal tank i dont like going to low with it....really hurts the wallet. Im bummed if it gets to 1/4.

Havent unwrapped the splices yet, but power to the pump was solid above 12, even at the internal pump plug. Resistance was good too. I was looking for a ground and couldnt find it. All the wires go into the main loom and the relay box. I thought there should be an external ground?

So you dont think it will prematurely wear out the FPR flowing that constant pressure to it?

Hey thanks a bunch for the help!

[j cAT]

I think your good.

the splices need be sealed especially in the rust belt/deicing regions.

water gets to those they will begin to COOK and the wires will vaporize.

then the pump burns out with low voltage.

there should be a point on there where it goes to the frame for grounding

not sure with yur express.

[whateverz]

Originally Posted by j cAT

I think your good.

the splices need be sealed especially in the rust belt/deicing regions.

water gets to those they will begin to COOK and the wires will vaporize.

then the pump burns out with low voltage.

there should be a point on there where it goes to the frame for grounding

not sure with yur express.

Worth a look at the wires then, not a big salt problem here but it did come from GA. Have to take another look for that mystery ground.

And thanks, I think its fine too. Thats what a return line is for, right. And if you had a performance inline external pump it would have to do that.

Time will tell....