Question about 1983 Mercury Grand Marquis

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1998 Mercury Grand Marquis Fuel Pump Replacement

I have a problem with a 1998 Mercury Grand Marquis. I have replaced the spark plugs because of a hesitation problem. I got a code that stated a misfire on cylinder 4. My father has not ran the care for about 2.5 months prior to it running. After replacement of the spark plugs I tried to start the car and it did not run. I check for gas and NO pressure was on the fuel rail. I replaced the fuel filter and at that time I checked for fuel coming from the fuel pump. I had my dad turn ON and OFF the ignition key to run the fuel pump. Neither a sound nor gas was being pumped from the gas line. I am next going to check for power to the fuel pump. All fuses tested good. I also changed out the fuel pump relay with an exact match from another relay. I can hear it click under the hood when turning the ignition to ON. MY QUESTION: Is it necessary to drop the fuel tank when replacing the fuel pump assembly? It looks accessable from under the car. It is located just behind the rear axle in the middle of the fuel tank. If I jack the car up with proper supports or put it on a car lift, it looks like I could remove it without dropping the tank. Do you know this to be true? Please let me know Thanks.

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You can try just resetting the fuel pump switch located in the car

the switch is originally in the car for in case of an accident, however, if changed, chances are you also have to reset it

in my 98 grand marquis, the switch is on the left side of the trunk

Posted on Mar 19, 2009

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NO you do not have to drop the tank! The whole assembly can be maneuvered out with the tank in the car! I have personally done this myself on my own 98 grand marquis. dont waste your time dropping the tank.

Posted on Jan 25, 2009

  • Bimmerknut Oct 15, 2010

    Pcastel, please tell me how you managed to do this. I'm working on a '98 now.

    Long story short here.
    Car overheated due to the plastic intake.
    Car has been sitting with 1/3 tank of fuel for 3 years.
    Battery cables were rotted...

    This past week I....
    Put the upgraded intake on for the 4.6L engine.
    Put new battery clamps on the cables
    Put in new battery
    Changed oil and oil filter
    Put in new fuel filter

    Went to turn engine over and no fuel is getting to the rail. I know this because I don't hear the in tank fuel pump come on when I have my wife turn the key ON and my ear against the open fuel tank filler tube. I pour a scant bit of fuel in the throttle intake and she fires right up and runs for the few seconds so I know we have spark.

    I get power everywhere including the switch in the trunk. I decided to try to check at the fuel pump but the wires can only be disconnected from INSIDE the tank, or basically you pull the pump out far enough so you can unplug it....*(or so I thought)....

    I figured I might as well drain the tank anyway so I remove the filler tube, disconnect the fuel and vent lines. I'm ready to drop the tank now with the two nuts holding the straps in place.

    Problem: How the hell do I disconnect the fuel pump? I can't pull it all the way out. Even if I drop the tank, I will have a fuel pump dangling from the harness. Any advise would be greatly appreciated.

    Thank you very much~!


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Hi there.... In regards to dropping the tank to get at the fuel pump, Yes you have to drop the tank. It's not only the pump that comes out of the tank it's the whole assembly including the float which tells you how much gas is in the tank. you have to have enough room to manuver the float out and the whole assembly is approx. 6-10 inches long. Hope this helps you out

Posted on Jan 09, 2009

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