Question about 1978 Mercury Grand Marquis

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My 1978 Mercury Marquis ''stutters'' and shakes a little when it gets to the shifting range between 2nd and 3rd (roughly at 40 mph). Scared to take it above 40 mph!

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  • anabethminx Jun 24, 2009

    I changed all these last night. I also replaced the fuel filter. The car still suffers from the same symptoms.

    I would describe the "stutter" as the way it feels when you stop at a light, put your foot on the brake and start tapping the gas. It's as if it's struggling to do something.

  • Marvin
    Marvin May 11, 2010

    suggest u try live chat option

  • Marvin
    Marvin May 11, 2010

    Is this a missfire? if so have the spark plugs, spark plug wires, distributor cap and didtributor rotor been replaced?



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make sure your vacuum advance doesent have a slow leak, attach a spare piece of vac hose to the vac advance mod on the distrributor and s u c k on that hose., it should hold air and not leak make sure you dont have any other vacuum leaks. the vac mod on the tranny could have the same problem. open the jets on the carb a little by turning counterclockwise, you see the engine mellow out. theres two screws up under the front of the carb might need a rebuild, fuel filter could be half clogged. and then re time the engine..


Posted on Feb 10, 2011

  • Jude Meredith
    Jude Meredith Mar 05, 2011

    check egr valve. its a silver disk looking thing on the top of the engine . it has a vacuum line running to it. plug that and run it and see if it stops doing that. if it stops then thats it.




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