skysnipe

Ok, i have a rather complicated problem with my car, i am not a mechanic, nor a car person in general so please for give me if i am a little car-illiterate.

Ok, the problem is this: When it has a full tank of gas it is fine, when it doesnt though, it dies when it stays stationary for too long, like when at a stop light or stop sign for too long, and sometimes it wont start at all and i have to wait a bit and try later (like 10, 15 min) then it will start. we've already replaced the fuel filter, the distributer, all the spark plug wires, and gotten a new battery, oh, also, it doesnt like to start if the heater, radio, or headlights are on, could be just a coincidence, but, like i said, i dont know much about cars

Car specs:
'83 Grand marquis
302 V8 engine
Fuel Injected
Recent oil change
fresh gas in it
has had injector cleaner ran through it


Any help would be greatly appreciated
Thanks

 

Lambykin

Hey, no need to apologize - you actually explained the problem fairly well. I use to own an '85 Crown Vic (virtually the same car).

Fuel Injected, eh? And seems to run fine with a full tank of gas, but stalls when it gets lower, and doesn't want to start when high-drain electrical items are on?

Sounds to me like you have a very weak battery, and/or a bad alternator. I assume by not starting, that the starter doesn't engage (maybe you just hear a click when you try to start the car?) or the engine turns over very slowly...

OK, now you might ask, "Well, that's fine, but why does the car run fine when it has a full tank of gas?" Well, fuel injected cars have an electric fuel pump. While I can't say with 100% certainty (I'm not there to see for myself), I'm guessing because the battery is weak that your fuel pump isn't operating as it should (meaning it's pumping less gallons per minute than it should). Why does it run with a full tank of gas? It could be that with the weight of approximately 20 gallons of fuel in the tank, this is "helping" the pump a bit. The pump is acting as a weak syphon, and the weight of the fuel itself is doing the rest to flow to the injector (should be throttle body injection in your car). There's less natural syphoning action as the fuel level drops, the pump isn't working optimally (possibly because of the battery), and you get your stalling.

You'll have to have your battery tested - if it's fine, and holds a charge, your alternator could be weak. If you have one of those batteries that has an "eye" (it's usually a bright colour like blue or green when fully charged) I suggest you clean it off and look into it. If it's black, this means the battery (at the very least) needs to be charged. I'm guessing it won't hold much of a charge anymore.

Since you're not a car person, you'd be best to take your car into a service station & have them inspect the battery & charging system. Only problem is, a lot of shops love to do a knee-jerk reaction of automatically replacing an alternator just to make money on a part that didn't have to be replaced. Then again, you said your vehicle is a 1983 model - if you have the original alternator in the car still, it might be wise to let them replace it if they tell you it's bad. Alternators don't last forever, and 25 years out of one is good service.