96 SL with bad accelerator pump???

Discussion in 'General Motoring' started by Mike Swift, Feb 13, 2007.

  1. Mike Swift

    Mike Swift Guest

    Yes I know that Saturns do not have carburetors, and hence accelerator
    pumps, but thats what the symptoms are. My mechanic has checked O2
    sensors, thermal sensors, plugs, coils, throttle position sensor, and
    nothing helps. Each time you depress the accelerator peddle the engine
    stumbles like the mixture is going lean. It recovers in about 1/4
    second, and runs strong until you increase the throttle setting. Then it
    stumbles again. This is annoying when shifting gears.
    Saturn factory manuals don't mention any troubles that fit this
    description, so they are of little use in debugging this problem.
    Sometimes I wish it had a carburetor so I could fix the problem. :)

    --
    Mike

    Some say we must tax corporations more. What they do not understand is that
    corporations do not pay taxes. One of our governments conditions for their
    existence is they collect the taxes from their customers and pass them to
    the government.
    Mike Swift
     
    Mike Swift, Feb 13, 2007
    #1
  2. Mike Swift

    Bob Shuman Guest

    Just wanted to suggest that the stumble on acceleration could very well also
    a sign of running too rich (and not necessarily too lean). This appears to
    be the first message posted in this thread from my news server so I have no
    idea what other symptoms or actions you have taken.

    How exactly has the mechanic "checked" the items you have listed? Is that
    mechanic competent and familiar with Saturns? Are the plugs and wires new
    and are they gapped correctly? Have the fuel and air filters been replaced?
    Are there any obvious vacuum hose or manifold leaks? Is the EGR valve
    functioning properly? Have you looked for and cleaned off corrosion on the
    coil towers? Are the engine and body ground wire connections all clean and
    tight? Are all the injector connectors clean and tight? When was the last
    time the throttle body and AIS were properly serviced? Have you removed the
    plugs and were they carbon fouled or oily?

    Good luck. Post what you find?

    Bob
     
    Bob Shuman, Feb 13, 2007
    #2
  3. Mike Swift

    Mike Swift Guest

    Thanks for the quick response Bob. Plugs are new and gapped, EGR valve
    is working, air filter has been replaced in the last 5000 miles, plugs
    are clean, engine ground wires are good and tight, and the throttle
    position sensor has been replaced. Im not sure what you mean by
    "throttle body and AIS were properly serviced". My mechanic, and his
    other two men have had at least 20 years experience on almost every
    brand of car including a hundred or more Saturns.
    This morning he has found that the fuel pressure is 35 psi, and should
    be, by the book, 45 psi minimum. He is going to replace it, and I hope
    that was the problem.

    --
    Mike

    Some say we must tax corporations more. What they do not understand is that
    corporations do not pay taxes. One of our governments conditions for their
    existence is they collect the taxes from their customers and pass them to
    the government.
    Mike Swift
     
    Mike Swift, Feb 13, 2007
    #3
  4. Mike Swift

    Bob Shuman Guest

    Thanks. Here's to hoping it is the fuel filter and this solves your problem,
    assuming that is the "it" that is being replaced. If not, the fuel pump
    will be a bit more expensive.

    Bob
     
    Bob Shuman, Feb 13, 2007
    #4
  5. Mike Swift

    NapalmHeart Guest

    Which plug gap spec are you using? In '96 the spec was changed to .60", but
    then was changed back to .40".

    The throttle body plates are notorious for accumulating carbon and benefit
    from a good cleaning with TB cleaner and a nylon bristle brush.

    Ken
    --
    "A drug is neither moral nor immoral - it's a chemical compound. The
    compound itself is not a menace to society until a human being treats it as
    if consumption bestowed a temporary license to act like an asshole."

    - Frank Zappa
     
    NapalmHeart, Feb 15, 2007
    #5
  6. Mike Swift

    Mike Swift Guest

    This saga is getting a little long, so I am going to top post this so
    those knowing the tail won't have to page through all of the details.
    My mechanic has replaced the fuel filter, no solution, fuel pump, no
    solution, and then fuel air ratio sensor, but still no solution. I am
    going on a trip of about 1400 miles starting tomorrow, and when I get
    back will see if the Saturn dealer can diagnose the problem. I really
    want to find the exact cause, Im an engineer if you could not guess, and
    not just replace parts until it works.


    --
    Mike

    Some say we must tax corporations more. What they do not understand is that
    corporations do not pay taxes. One of our governments conditions for their
    existence is they collect the taxes from their customers and pass them to
    the government.
    Mike Swift
     
    Mike Swift, Feb 15, 2007
    #6
  7. Mike Swift

    njot Guest

    I bet you tht this is the EGR control solenoid. It is turning on EGR
    too soon, causing the stumble.
    I'd start here and go from there.
     
    njot, Feb 19, 2007
    #7
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