Hello all,

I purchased my 1983 Mercury Grand Marquis 7 years ago from a man in Virginia for a great price and its absolutely mint.

Ever since I've owned it, I have had a stalling/starting problem. I have just about replaced the entire ignition system (i.e., battery, Alternator, voltage regulator, cap/rotor, plugs, wires, coil, capacitor, ignition module, PCM, starter relay...) and the problem persists.

Last year had, by far, been the worst of my luck and I had finally given it up to Ford to have it fixed. They "found" the problem and it had apparently been my PCM that was giving out a ground as an ignition signal. Their diagnosis: Short in the PCM. 800$ later, I had it running like a dream. I had it running for a month and put it away for the winter. Every couple of weeks I'd start it up and it was flawless.

Mid way through the summer, my problem is back. Same old same old. The problem arrives completely at random. I'll be driving and it runs like it always should and occasionally, it will stall at idle at a light, stop, etc. When I try to restart, it will just crank and no fire. i have wiggled around my harnessing around and sometimes it will work after many starting attempts. Other times, it won't start at all.

All general diagnosis check out o.k.. Battery voltage is fine, all components replaced, fuel pump sends fuel. Just no fire. There are no performance issues. Everything runs just the way it should. The car will just cut out and not start after ward.

What else have I and, especially Ford, overlooked? Is there a way to bypass a circuit or better diagnose the problem? I DO want to rip out the current Duraspark/ fuel injection system and drop in a perfomance/carbureted system but I only have the means to afford its maintenance for the time being.

This owning experience has only been frustrating and almost depressing as I really love the car but it has only created headaches for me.

If there is a hope for expert advice and diagnosis, I'd be eternally grateful! I only want to enjoy driving the thing with out it stalling on me!

 

Two things come to mind. Did anyone check for loose or poor connections at the ignition module? Also the pick up in the distributor could have a faulty ground or itself be defective.

 

We used to run into sensors shorting internally and causint the symptom you describe. Most of the time we found the cannister purge solenoid under the battery would short internally when it got hot. It would take all the voltage from the PCM and shut the car down.

 

I have a durasparkIII system so there isn't any pickup in the distributor. Also, my ignition module is relatively new and all its connections had been verified by myself and Ford. I don't really see that as being the problem, but who knows..

As far as the canister purge solenoid, if it is defective, would the stalling/no start problem be intermittent,random, or constant? In my case, i will manage to get the car to start by wiggling the harnesses or in other cases, the car won't start for days even weeks..

Would the solenoid need to be be replaced, or its there a simple bypass i can do for now? like mentioned before, the stalling happens when I come to a stop. Otherwise, i can be rolling for hours without any stalling at all.

 

The purge solenoid will cause a very intermittent problem. We used to get them running and park it outside and it may or may not start when it is put into use. You can unplug the solenoid to see if it helps any. If it is not it, it will do no harm to the vehicle.

 

There aren't any electrical connections at the canister under the battery. There is only a vent line for the gas tank. I unplugged it anyway and still no start. I proceeded to wiggle all connections at all sensors around the engine and miraculously, I got it to start! I'm letting it idle for a while to see if it quits. I know this is not a permanent solution and I'm sure, as always, that the problem will return. I noticed that the crank position sensor is original. could that have anything to do with it?

 

I have been posting in another forum and apparently for '83 models, they introduced the crank position sensor. This particular year had a very problematic sensor and my problem well describes a faulty CPS. I just ordered one off of ebay and we'll see how things go once I receive and install it.

 

If that happens again before you get the replacement crank sensor, shoot some cold water on the crank sensor and if it starts right up it's a good bet the sensor is defective.

 

Thanks! Does this mean that the sensor is really sensitive to heat? This is my replacement part:
Wells SU213 Crank Position Sensor

I have purchased Wells products in the past and have no complaints. Seeing that this is aftermarket, is it more reliable than older replacements?

 

Wells has good stuff. They make reliable products. If it were me, I would let that car run until it quit then try to restart it if it doesn't restart right away pour the cold water on the crank sensor and if it restarts then, it would eliminate all doubt. Just don't let the engine cool down while you go for the water . Have some handy close by. I have done this several times and never had a come back after the change of the crank sensor.