My Dad has a 1965 Mustang but years ago, he put a more modern 5.0 in it. The EEC unit is a version IV. Based on the engine wiring harness, I think the loom is from a 1994 Mustang. It took me quite some time to find a diagram that the color codes mostly matched and the relays matched. ( One is the the fuel system relay and the other is the A/C wide open throttle relay ) . Some months back we changed his fuel system to a tank with a built in fuel pump from the original 65 tank and an external fuel pump. After installing the tank and hooking up the wiring, I wasn't getting power to the fuel pump and I had to trace all the wires and spend lots of time reading forum posts and looking for the right wiring diagrams. Then is started working with the wiring back the way it was after I installed the tank.
Here is the problem we have now. If the car sits for a few days, the startup is really poor. It backfires a few times, the RPM is really slow and it might die. If you keep working the pedal or try again, it will finally clean up and run. Once it runs a bit and you shut if off, it starts up like it always used to.
I don't know if the EEC is not getting good constant power and eventually forgets all the sensor values it "learned" if a sensor is bad or has a loose connector, or, if a cylinder is getting flooded when sitting, due to a leaking injector. It could be the EEC is going bad.
Using a code reader isn't too helpful because the engine does not use all the plugs from the wiring harness and the EEC records things like a purge canister error since there is no canister.
On a side note, " Starting like it used to " is a little odd because ever since he's had this engine in, with the newer electronics, he would fire it up right off, it would die, and then a second attempt would fire up fine and stay running. It wouldn't die in an ugly way, it would just shut off, like it ran out of fuel. That's why we changed the fuel tank setup. To try and solve this.
I hope there are some EEC experts in the forum still.
Here is the problem we have now. If the car sits for a few days, the startup is really poor. It backfires a few times, the RPM is really slow and it might die. If you keep working the pedal or try again, it will finally clean up and run. Once it runs a bit and you shut if off, it starts up like it always used to.
I don't know if the EEC is not getting good constant power and eventually forgets all the sensor values it "learned" if a sensor is bad or has a loose connector, or, if a cylinder is getting flooded when sitting, due to a leaking injector. It could be the EEC is going bad.
Using a code reader isn't too helpful because the engine does not use all the plugs from the wiring harness and the EEC records things like a purge canister error since there is no canister.
On a side note, " Starting like it used to " is a little odd because ever since he's had this engine in, with the newer electronics, he would fire it up right off, it would die, and then a second attempt would fire up fine and stay running. It wouldn't die in an ugly way, it would just shut off, like it ran out of fuel. That's why we changed the fuel tank setup. To try and solve this.
I hope there are some EEC experts in the forum still.