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Thread: V.W Beelte 98 2.0L

  1. #1
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    Default V.W Beelte 98 2.0L

    Hey, Ive been fighting a obd2 code p1128. Ive tried everything I know... 02 sensor Mass air flow sensor new spark plugs and wires ect. Ive narrowed things down to a fuel delivery problem. Except the fuel pressure is at acceptable range and the fuel pressure regulator is working.But... if I choke off the return line to the gas tank the car will run. As of now I have the fuel pressure regulated to approimately 70psi by restricting the return line and the car runs fine and the check engine light is off.So does anyone have any suggestions I know I cant leave it like this but I was tring to see if it would help clean out the injectors by add the extra pressure and adding lucus injector cleaner? Maybe their plugged or I have the right pressure but maybe the volume is too low. What do you think?
    Last edited by Darb; 03-16-2011 at 09:47 PM.

  2. #2
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    Hi Darb,

    What is the fuel pressure? Is it as specified? The fact that the problem goes away when you clamp-off the return line sure sounds like a pressure regulator problem, but I guess if the injectors were dirty and restricted the amplified pressure might overcome the reduced flow. If that's the case, a pour-in-the-tank injector cleaner will most likely not help. You could try the type of injector cleaner that you connect to the fuel rail; we've seen successes with that method.

    Other things you can check:
    Leaks (false air) in the air intake system
    Exhaust system for leaks (that one is kind of a remote possibility)
    Secondary air injection system for leaks
    Vacuum lines for leaks

    I hope something turns up!

  3. #3
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    Hi,

    Thanks for the reply, The fuel pressure according to the the manual is 44psi.At idel the pressure runs steady at 32psi. When I apply the throttle the pressure jumps up to approx. 40-42psi,but the motor stumbles and acts like its starving for fuel. So far, Ive left the return line restricted and been driving the car and it seems to be running better and getting better fuel mileage. Do you think a 4psi drop in fuel pressure would cause the problem? It seems like I need at least 60 - 70 to make it run right.
    Can you buy that injector cleaner at an auto parts store? Does it come in a kit with connections and fittings to feed the rail?
    Thanks again for your input.
    Darb

  4. #4
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    Darb,

    You have 32 psi at idle, but it should be 39. So you're short 7 psi. Could be enough to cause a problem I guess.

    As far as the fuel injector cleaning kit, not sure if most auto parts stores carry them; you'll have to call around. You might have to contact a tool dealer (Snap-On/Mac, etc.).

  5. #5
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    Thumbs up

    Ok, thanks for your help.
    I think it probably is a weak fuel pump. I'll let you all know what I find so maybe it will help someone elsse in the furture.

  6. #6
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    Remember though, you were able to measure 70 psi with the return line clamped off, so the low pressure could be a result of a bad pressure regulator. Then again, it could be the pump (if it isn't able to move enough fuel, but still able to produce the pressure, albeit not quickly enough).

    Anyway, let us know what you find.

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