Question about 1991 Mercury Grand Marquis

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Battery, battery, battery!

I just changed the alternator on my 91 Grand Marquis. That should have taken care of my problem with power supply. The battery was tested and said to be good. Now the darn thing just keeps on stalling, whether after using the brakes around a turn, or just simply at idle at a stop. The battery light was off after new alternator put in and once again it has come back on. I don't know that much about cars, but I sware this car has a ghost in it or something, just stealing my power and functionability. Should I get a new spark plug, or spark plug wires etc.? Please help me, I am completely lost.

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  • grandmarky Jul 11, 2008

    Thanks man. I appreciate your concern for my problem with battery. I did some of the suggestions you mentioned before posting this request for help....I had some other issues with this car- light to heavy annoyances at times-mainly gas is getting me hard, therefore I have sold it and gotten a new car...just before I did this however, at Adv. Auto guy made good assumption that there was possibly cylinder misfiring in engine, and maybe one of spark plugs was burnt out. Basically it just started stalling way to much with braking or idling at lights...Thanks again though for your concern- I like the way you think.



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You do have a short in the electrical system, test this by putting a freshly charged battery and connect the negative to the battery then try to just scratch the positive wire to the battery and watch if there is a big spark that would be produced. if there is then you have a short that is draining your battery. if there is a small one . that could just be your clock or radio. if you have an ammeter ( a tool to measure current) you can take the current that the car is drawing as you put the positive wire to the battery.

another test is start the car. get a volt meter that would measure dc voltage in the range of 20 volts. then measure your battery voltage. it should read at least 13.8 volts dc. turn on your head light, it should still read at least 13 volts dc. then lastly, tun on your ac if you ahve one. it should still read above 12 v. at least 12.5 v. that means your alternator is charging.

all of the test and readng are on idling state.

then rev the car to 2000 rpm if you have an rpm meter and all of the voltage should increase a little bit but not exceed 15 volts.

if it does exceed 15 volts then you have a bad regulator that fries batteries.

i hope i was able to correct your problem.

Posted on Jul 08, 2008


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I would use 10W40 in the 96 and 5W20 or 30 in the 2002.

For the 96 with sluggishness, you need to gently clean the MAF sensor wires with carb cleaner and a toothbrush. It is in the air intake tube. After cleaning, disconnect the battery for 1/2 hour, then reconnect so the computer can relearn the clean sensor. Drive for 10 miles, it will run rough until it relearns.

Section 03-14: Engine Controls, Electronic 1996 Town Car, Crown Victoria, Grand Marquis Workshop Manual
DESCRIPTION AND OPERATION Mass Air Flow (MAF) Sensor The mass air flow sensor (MAF sensor) (12B579):
  • is mounted on the corner of the engine air cleaner (ACL) (9600).
  • uses a hot wire sensing element to measure the amount of air entering the engine; air passing over the hot wire causes it to cool.
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The mass air flow sensor hot wire sensing element and housing are calibrated as a unit and must be serviced as a complete assembly.

Mass Air Flow (MAF) Sensor


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