91 GRAND MARQUIS 5.0 LITER

  • Tiny
  • Nk972003
  • 1991 MERCURY MARQUIS

I have a '91 Grand Marquis and when I turn on my car there are 1 or 2 surges in rpm and then it cuts out unless I hit the accelerator immediatly. After that it runs fine until I have to stop at a light or slow down and then it cuts out again. I had this problem before except it only happened when I ran the AC or heat but it would only surge and not cut out. ( By the way AC does not coo if that helps) I had a major tune up about a month ago and put in concentrated fuel treatment but it still happens.
Any help would be great.

Thanks,
Nikki

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Sunday, December 10th, 2006 AT 11:02 PM

1 Reply

  • Tiny
  • Merlin2021
  • EXPERT
  • 17,584 POSTS

Surges are caused by vacuum leaks. Get a can of spray gumout, start the car, or have someone else do it and spray around vac hosoes and the corners of the intake manidold, when a change in RPM occurs you are in the right place. 5.0 engines have a problem with the aluminum intakes disolving at the corners! Also were the PCV plugs in at the back, top middle of the intake, the rubber bushing becomes brittle. This cauases oil and air leaks!

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Monday, March 5th, 2007 AT 6:59 PM

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