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Old 08-21-2010, 02:06 AM
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efi question

i got a 94 buick 3100 v6 an was wonderin if this is a sign of bad pump or injectors if i check to see if theres psi in the fuel rail right after i shut it off theres good amount of psi if i run it again an not check it for like an hour theres no psi dosnt even drip fuel out the check valve

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Old 08-21-2010, 08:54 AM
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Whats the problem your having? I would think that it would be normal for the pressure to drop down after an hour or so. But then I'm no mechanic.
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Old 08-21-2010, 07:05 PM
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The key is not having pressure but HOW Much pressure. Its good to connect the pressure guageand run it and then put it under load and see how much it drops or raises.
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Old 08-21-2010, 07:16 PM
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that 3100 is a chevy motor ( in a buick no doubt) good ol gm crossdressing. Anyhow...put a gauge on the pressure test port.Check it while running. should be around 41 to 47 . It should increase from where it is at idle when you accelerate the engine ( maybe 5-7 lbs.) after you shut it off the pressure will drop to probably 20 lbs. This prevents vapor lock.somewhere around 15 or 20 is ok.It should hold pressure for around an hour .It will drop to zero in maybe 45 min to an hour. That is good. If it goes to zero right away then the check valve at the pump is probably defective. If you drive the car and then when you accelerate thecar loses power and the gauge drops off sharply then there is a fuel starvation problem.Maybe the filter is on the verge of plugging solid or the pump is not able to keep up with demand.
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Old 08-21-2010, 08:03 PM
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what started this was the psi regulator vac was bad i replaced it an it ran better but still at serton amount of throttle it stumbles kinda like when runing outa gas but not all the time

just dont want to throw parts at it till i find the prob tho
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Old 08-22-2010, 05:48 PM
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read my previous post. Do the fuel pressure test while driving and see if the symptoms occurr when the gauge indicates a pressure loss.
Have you checked/ changed the fuel filter? ever?
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Old 08-22-2010, 05:56 PM
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will be doin that test asap
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Old 08-22-2010, 06:08 PM
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Good man. It will tell you what is up .If you are standing on the gas and the performance starts do drop off and the gauge is heading towards 0 then you know which way to go.If it does check the filter first. If Louie armstrong cant blow through it neither can your fuel pump, get it
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