Questions and Answers

Grand Marquis Runs Ratty Q. I have an 1984 Mercury Grand Marquis, 302, carb, automatic, 70,000 miles, P/S, A/C, cruise control. Anyways, about three weeks ago the car started running bad. I drive to Phoenix and Tucson once in awhile.

Well after about 45 minutes to an hour of driving on the highway I noticed that the car would start to act sluggish at certain speeds then speed up and run normal, when I would give it some gas. Then the car would run rough and die when at an idle. It does not act this way when I drive to and from school, about 15 minutes away. Only when I do highway driving. It also runs normal after I let it sit for about an hour or so, after it dies. However, it will start up right after the engine quits. Can you tell me what might be wrong?

Jason

A. Before looking for the weird stuff, make sure that the basics are in good shape, spark plugs, distributor cap, rotor, wires, vacuum leaks, etc. In your case I would also make sure the fuel filter is okay as well. I would just replace it and know that it is good. The problem could be as simple as a clogged fuel filter. When you change the inline filter, don't forget the one inside the carburetor itself.

That carburetor has a feedback fuel control. I have found that the feedback solenoid usually goes bad on these carburetors. Since you need a scan tool to check the solenoid and the computer output to it, you'd probably be better off taking it in to have it checked. It may also be that the carburetor itself needs an overhaul. From the year and milage you obviously don't drive it much and it is possible the insides are gummed up. There are some very small passages inside the carburetor that doesn't take much to clog.

Information provided courtesy of ALLDATA