IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: dennisL on September 06 2012, 04:59:53 PM
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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
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you can squeez the hose in front of engine by power steering box
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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.
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gummed up injectors??
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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
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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.
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i hate dropping the tank. by far a PITA
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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!! :player:
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God gave us two knees and an elbow for putting it back in
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Anyone want 15 gallons of Sunoco Ultra? I'll need a place to store it when my new fuel pump arrives.
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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
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seems all too logical! :)
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Why not just drain the tank via fuel rail & some hose into a few 5 gal jugs?
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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.
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Dropping the tank isn't that bad. Car ramps and a 5gal bucket are the perfect height to keep you out of trouble when the tank comes loose. The worst part of the whole job is the dust.
If you detonate hard enough to crack two pistons and have to rebuild the entire damn engine because of it you'll feel pretty pissed (trust me, I know!)
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Thanks Earl - the 5 gallon bucket idea is something I hadn't thought of.
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(http://www.turbobuicks.com/forums/attachments/buick-v6-turbo-tech/18489-how-install-intank-fuel-pump-im001583.jpg)
It's just low enough to get in there, blow off the dust and disconnect the hoses and wiring
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A floorjack & a peice of plywood also works well for getting it back in the aproximate spot.
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A floorjack & a peice of plywood also works well for getting it back in the aproximate spot.
I have done that - but if there's any amount of fuel left in the tank, it will get unstable if moved too quickly.
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I have done that, but, I find it easier to just use my elbows and knees and slide it down on top of me...then I slide out and pull the tank from under the car once I have wiggled out from under the tank....easy if there are only two or three gallons in the tank
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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!! :player:
Which is part of the process of "dropping the tank." You cant just leave it off. Lol
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Well the new pump arrived today but all I had time for was to drain the tank and disconnect the hoses and harness. Tomorrow is "drop the tank" day. Right now its time for a beer. :atbeer:
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The tank is usually a 2 beer job from start to finish so your halfway home after the 1st beer! :atbeer: :player:
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Good luck Dennis!! :atbeer:
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God gave us two knees and an elbow for putting it back in
LOL , been here, spit,spit (20 year old road debris.......)
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Don't forget a "Hotwire" kit if don't have one already, or maybe best to add after ,if problem remains try the Kit
Enjoy!
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I've got a hot wire setup so voltage at the pump is good.
Well I changed the pump and added a new bulkhead harness from Racetronix. Their pump installation kit and harness is well made. The only issue I had was the polarity was reversed on the bulkhead to pump wires which I fixed.
I rebuilt the Accufab regulator, adjusted it to 43.5psi (line off) then took a short test drive. I now get 53psi fuel pressure with 16 lbs boost. Doing the math indicates I should see 59 psi so my question now is "Should I worry about the missing 6psi?"
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yes...might start with the gauge
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I have two pressure gauges besides the one on the car but they're old (like me). The one on the car is new but its not one of the "big 3" brands. (I was trying to save a few $$.) Can you recommend one that I could use as a reference to "calibrate" the others?
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maybe an ashcroft or similar
When you get old like me, everything seems better
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http://www.ihadav8.com/forum/index.php?topic=3547.msg53179#msg53179 (http://www.ihadav8.com/forum/index.php?topic=3547.msg53179#msg53179)
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