Question about 1981 Ford F 100

1 Answer

302 v8 missfire on no2 and 3 cyl on idle and low rews.no mis on high rews.compression good on all cyl.spark on plugwires,no reaction on idle if plug wires on no2 and no3 is removed.engine does notrew up smooth,backfire throw exhaust,new point,condensor,coil,plugs,p/wires,reset timming

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  • gjecarriers Jul 23, 2009

    did replace intake gaskets and carb gaskets, did not solve problem.

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  • Ford Master
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It sounds like you have covered the basics. Fuel, spark and compression are all that are needed. I would start by looking for a vacuum leak either between the cylinder head and intake manifold or at the base of the carburetor.
Use a can of carb cleaner and lightly spray at the intake gasket area of 2 and 3 and see if the idle smooths out. Also spray at the carburetor base on the side near 2 and 3 to see if the idle smooths out.
If that is unsuccessful, you may have to consider the intake manifold gasket has burned through between the exhaust heat riser port located between the two.
There is a tendency over time for the exhaust to deteriorate the gasket in that area or the other side, 6 and 7.
Consider it and let me know.
Regards,

Posted on Jul 21, 2009

  • Bruce Bracey
    Bruce Bracey Jul 23, 2009

    Did you just replace the intake gasket in the past 2 days or was it replaced before the 21st. Was the intake manifold replaced with a new one? When you replaced the gasket, was a straight edge used to check for warp on the head and intake manifold?



    If the compression is good and the spark is good, the only thing left is air/fuel. If the air fuel ratio is correct, the cylinders will perform normally. If it is contaminated with an air leak,exhaust leak or coolant leaking in you get the miss-fire.



    Let me know.

    Regards,

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