Fuel pressure or lack thereof

[dennisL]

So I finally get around to connecting my fuel pressure gauge to PowerLogger and notice the pressure is not increasing with boost.  So I change the fuel filter which needed changing anyway.  It doesn't fix the problem.  So I order a rebuild kit for my Accufab adjustable regulator.  While waiting for that, I replace it with my old Bosch 237 reg that has the top pushed down for 45 psi (line off).  I logged everything during a very short run and still the fuel pressure during boost (and my AFR) are crap.  So, I have two questions ...
1- Does the above point to a bad fuel pump?  Its a Walbro 834 that is 3-yrs old with 300 miles on it.
2- The Buick fuel pressure troubleshootin g chart says that if I crush the fuel return line I should get 75 psi.  Is back by the tank the only place to get to a rubber hose on the return line?
3- OK three questions, I would like to prove that the pump is bad before I drop the tank.  Is there a way to do this, or have I already done it?


I can post a screen snap-shot of the PL data if anyone wants to see boost vs f/p.


Thanks,
Dennis

[Scott87]

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[PacecarTA]

you can squeez the hose in front of engine by power steering box

[earlbrown]

Squeezing the return to measure deadhead pressure can verify that your pump is strong but it can't verify that your pump is weak.

 If you'd got the old fuel filter, cut it open and see if there's any flakes, hose liner, or pump debris in it. That's an easy test that's pretty telling.


  I'd drop the tank and do an exploratory on GP.

[phil_long]

gummed up injectors??

[84 BuickGNYorkPA]

So I would want to verify the accuracy of the electric gage, do you have a mechanical gage that you can tape to the windshield just to confirm the electric gage?
The other thought is that you mentioned that the a/f ratio number are on the lean side... This has always meant that it's time to drop the tank and replace the pump for me.


Chuck

[dennisL]

Thanks guys for the advice.  At first I questioned the pressure gauge too, but the AFR and O2 confirms the lean condition.  I'll attach the PL screen so you can see it.  It sure looks like its "drop the tank" time and I'll have to replace the f/p to prove this one is bad.  I don't like it but I'm going to replace the relatively new Walbro with another one.  If the new one is crap, I'll just send it back.

[phil_long]

i hate dropping the tank. by far a PITA

[Just a Six?]

i hate dropping the tank. by far a PITA

Dropping it is easy.
The work comes when it's time to put it back in!! 

[Steve Wood]

God gave us two knees and an elbow for putting it back in

[dennisL]

Anyone want 15 gallons of Sunoco Ultra?  I'll need a place to store it when my new fuel pump arrives.

[84 BuickGNYorkPA]

If you could just baby it until the tank is almost empty, then change the pump..... I know, easier said then done... especially when that Mustang, Vette, Hemi, Fart can import, try to nudge you on at a light... and everyone knows this only happens when the car isn't 100% ready for action.


Chuck

[Steve Wood]

seems all too logical! 

[Just a Six?]

Why not just drain the tank via fuel rail & some hose into a few 5 gal jugs?

[dennisL]

I was just being silly as I do have two 5 gal cans so I only need to use up ~5 gals.  Like Chuck said, I'll have to take it out during "off hours" to avoid the Muskrats and ricers.  Oh and I did tell the wife that I'd put some in her Hemi 300C if she was really, really nice to me.  I know what you're thinking ... good luck with that.