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  1. #1

    Default No start in rain/damp weather: 1997 Suburban 1500 5.7 liter Vortec

    For 2 years , 1997 Suburban 1500 starts AOK in dry weather .
    When in rain / damp weather , engine cranks and cranks, but does not fire up .
    Next day when weather is dry , it fires right up.

    Mechanic replaced fuel pump in tank last month .
    Worked AOK 3 weeks .
    Now , the "no start in damp weather / rain" issue has just returned .

    Yesterday , I suspected moisture in distributor cap was causing the issue .

    Replaced distrib. cap and I saw that the front dist cap screw was not tight , suspect
    some stripped threads as it would not get snug.
    Used blue locktite glue to assist .

    Also saw that previously someone had used 3 zip ties to secure distrib cap tightly down .
    I did not replace the 3 zip ties.

    I am awaiting damp/ rainy weather to see results of changing distrib cap.

    If a no start when damp/rain still persists , what to check next ?

    It certainly sounds to be electrically related , but where ?
    What fuel supply items are subject to damp / moisture issues ?
    And how to diagnose them ?

    If it were fuel related , I should be able to spray starter fluid
    into ( ?? where??) and it should fire for a few seconds .

    That would be a piece of the puzzle .
    At least I could isolate an ignition issue vs a fuel supply issue .

    What advice can you offer?
    Internet searches often say damp/rain no start related to
    distributor cap moisture, but need a backup plan.

  2. #2

    Default

    I think you are on the right track, I had a Ford Taurus that acted the same way, I had to spray some water proofer on the distributor cap every few months, you can spray starter fluid into the air intake tube, take it off of the air cleaner and spray down the tube, good luck.
    Terry

  3. #3

    Default

    TM, thank you for your response .

    For those trying to spray starter fluid into the Vortec 5.7 liter engine, this is what I experienced :

    I removed air filter paper cylinder near passenger side fender .
    Sprayed starter fluid into the newly exposed remaining airway ductwork .

    Nothing happened on a wet damp day .
    I discovered that there was a closed doorway / valve that prevented the starter spray from reaching cylinder.

    On the following dry day , I replaced distributor cap and in the process I attempted to remove the square plastic
    black box above throttle body by twisting 1/4 turn a tall plastic tower .
    It did not release anything.

    Next, I removed the screw-clamp band securing the plastic flex ductwork onto the square black plastic box
    and also removed the hex head bolt that secures the
    square plastic box to the airway chamber ductwork ( what purpose is this ? backfire suppressor ?).

    Now , I believe that I had access to the throttle body .
    New distrib. cap installed.

    Weather was dry , so I cranked engine .
    It fired right up---ran very rough sputtered died .

    I saw the sensors in the airway ductwork and suspected that the sensor data was
    required to feed correct data to ECU/MCU.
    I covered the airway ductwork with my hands to block off fresh air from entering downstream of MAP sensor .

    Started up ,ran smoothly .
    Lesson learned -- that the square air box needs to be replaced or else the VORTEC 5.7
    would not run smoothly . Never saw that before .
    My experience was with carburetors, not fuel injection .
    Maybe this might help others.

    Still do not know function of that "extra" square air box just above the throttle body.
    It appears to be doing nothing , yet must have an engineering purpose.
    Also, that tall plastic tower did not release the square air box ; thought that it might provide
    easy access via the square air box .
    Any folks know about this black plastic tower and the square box unit?
    Perhaps this rambles into another thread topic.

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