Question about 2003 Mercury Grand Marquis
It only did it this summer when it was raining but now it does it all the time. been to quite a few mechanics and they say nothing is wrong just to get it back and still have the same issue
Could be the mass air flow(MAF) sensor. Unplug it, see if it keeps running. Unplugging it throws the PCM in default mode. Before replacing it, clean it and the throttle body with brake clean. Spray down the sensor and use a tooth brush on the throttle. Clean were the inside plate seats, top and bottom. After that if it still dies( I would put t on a scanner and read codes first) , replace the MAF. Ford did have MAF sensor that wouldn't pop a code, but were out of perimeters. Leaving it unplugged will result in really bad fuel mileage and take a toll on the catalytic converters.
Posted on Dec 13, 2016
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Posted on Jan 02, 2017
Ok odds are you just need a routine tune up. Plugs, fuel filter, air filter. Now this engine uses coil packs i think, so you wont have normal plug wires. The coil packs are individual and sit directly on the plugs. So it is possible you have a bad coil pack. These engines were known to have this problem in excess. So try the cheap fixes first. plugs, fuel filter...these two is the best two to try first.. The air filter wont cause a bad miss unless it is completely dobbed up. so just for your own good to change the air filter.Now if neither the plugs or fuel filter fixes this car try this. Each coil pack will have an individual plug on top of them. So listen closely to your engine. Unplug each coil pack one at a time, Now evry time you unhook a plug the engine should miss, so unplug one at a time, and if the engine does miss they are working properly. Now if you unhook one of these and there is no change in the idle of your engine, my friend you have found the problem. All you have to do if you find one that does not change the engine idle, you just go buy a coil pack and replace it. This should fix you right up
Posted on Sep 04, 2008
Sounds to me like the fuel pump is worn out. They DO wear out. And even though they seem to be working, the brushes in the electric fuel pump may not be contacting all the commutator, thus making the pump weak. It may start the motor but can't maintain normal running pressure (27-35psi). Have you run the car out of gas shortly before this problem surfaced? If you have then it's your fuel pump. It was damaged when the tank ran dry. Even though the pump may seem to be working, it's still badly damaged and needs to be replaced.
Just as Matmenzies has stated, get a fuel pressure gauge and test the pressure. I'd start with a complete check of all your vacuum lines. Check for cracks on the vacuum hose that connects to fuel pressure regulator on the fuel rail. Also, if you can, get a hand operated vacuum pump to check the regulator. If you can place a vacuum on the regulator and it holds, I'd say move on the fuel pump and check it.
BTW, if the fuel filter has been changed, you may want to check to see if it was installed backwards! Some fuel filters are valved and will cause symptoms like this. However, this is an immediately noticeable mistake and you haven't provided enough info for me to say more. I'd pull it and check that it has any flow at all. You could have sucked in a big dirt ball and blown it right into the new filter, effectively stopping fuel flow. Then I'd blow out the fuel lines, just to be sure.
Start with these 2 things and post what you find. We'll go from there.
Posted on Jul 09, 2009
It wouldn't hurt to change the filter, but it sounds like you got a bad batch of gas, if it was running good before you got gas.
Get a bottle of dry gas and put it in the tank, if there is any water in the gas, that will clear it out, also it wouldn't hurt to put a bottle of fuel injector cleaner in the tank, I use that stuff all the time to keep the fuel system clean.
Posted on Jul 17, 2009
check the back of the radio, make sure than the antenna, connector is plug into the radio, if it is, then replace the radio.
Posted on Jul 30, 2009
My 2003 Mercury Grand Marquis has the same problem. We found out it was the headlight module located under the dash above the gas pedal. The black box has wire connectors coming out of the back. Hitting the box worked for a little while, then I had to reach in the back and wiggle the wire harness. The dealership wants 500.00 to replace the unit. I consider Highway Robbery! They have installed a faulty piece of equipment on my Luxury car that could easily be life threatening but we know it won't be recalled until someone dies because of it. My husband was able to remove the unit and looked it over it had two circuit boards and he was unable to visibly see any problem or loose wire. He cleaned the connectors and used some electrical terminal grease on the wires, this improved it for a short time. The problem still exsists. I have sat for 30 minutes or more waiting for them to go through the On/Off cycle till they stay on for the 45 minute ride home from work. I have beat the box with my flashlight (maglights handle the abuse, my fingers and nails don't) till it came loose from the brackets that hold it. I leave my car running while pumping gas, short shopping trips and start it 20 or 30 minutes early before leaving for work. It is frustrating and dangerous. If this is the kind of quality in our American made cars it's no wonder they needed a BailOut! The only thing we have found to "fix" it is to find a used part that could possibly have the same problem shortly down the road or pay the theives at the dealership to replace it.
Posted on Dec 31, 2009
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