Everyone's a bit right on this. This is EEC III efi (or possibly a VV carb, but for the sake of argument, it doesn't matter). The CKP sensors were very notorious for getting "thermal", where they would work cold or hot and not inbetween and many, many other problems. Be sure to check the ground shield that wraps around the CKP sensor harness, to make sure it's there and not shorting something out as these engines from this era were not know for their superior sealing characteristic. One other thing to check is the EEC power relay; over time, i can imagine a problem very much like this. And of course, always check all wiring connections all over, as this is a pretty old boat, and the insulation will get hard and crack and peel off, etc, etc.

 

Just received the sensor today and installed it. The car decided to start and run prior to the change anyway but the car is still running and I hope that it will continue! The funny thing about my issue is, when it will happen would be typically at low idle like at stop sign or light. In other cases, the car will be running fine as usual and when I park and come back either in a few hours or the next day, the car won't fire over. It just chooses to work when it wants to. Hopefully the sensor was the issue!

 

Also, where can I locate this EEC power relay? My entire ignition system's components have been changed beside this relay. The car is clean and doesn't see winter. I have gone over just about every connection and ground. There can always be that "random" thing that I have over looked.

 

Thanks everyone for all the help! So far so good and I'm keeping my fingers crossed that the CPS was my last issue!

 

New discovery!!

Same old same old for the stalling / no start issue.

The problem came back and got my mind spinning.

I began to dig a little deeper and was testing for spark with a timing light. I wasn't getting anything. This obviously was telling me that there isn't any ignition signal hitting the coil. I use my multimeter and find that i'm only getting about 7 volts at the positive terminal of the coil while key is on ignition. I use a fused jumper from the 12v of the alternator to the positive terminal of the coil and i suddenly hear a click from a relay. I disconnect and reconnect a multitude of times and sometimes it'll click and some times not.

At this point i try to start the car. First few tries wont work and then it fires over! 5 mins later, it stalls. Try cranking again and it took a about 10 tries and it fires over. This time i leave it run for about 20 mins and its fine. I keep trying to start/stop and it seems fine. I then try to find the relay by turning ignition on and off. Turns out that its located mounted on the driver's side fender beside the cruise control unit.

There are 2 relays together in this location. One with a green connector and the other with a brown.

It seems to be that there is little info offered on such a simple item. Nothing in the haynes manual and not much online. I found the replacement part in Rock Auto's catalogue but i'd like to know what the other relay is. They are 30 years old and need to be both changed.

As I am by myself doing this, can someone tell me (if possible) what which connector (green or brown) is for the ignition relay and what the other relay would be?

All help greatly appreciated!

 

I recently bought an 83 Grand Marquis myself. Im having similar issues. i realize this thread is 10+ years old but by any chance do you have any photos, or remember how you finally got it ironed out? im having a problem even getting to what i think is the crank position sensor. Thanks

 

Just for kicks , where do you think the crank sensor is located?

I ask this question so I have some idea of where you should check next.