5.0l efi wiring diagram-anyone-?

[ivebeenbit]

does anyone know or have a diagram--i am trying to find out
what wire gives the engine computer a constant 12 volts
with the key in the off position for memory?

i feel this is why i have a starting problem the first time i start the
car

dave

[A Cobra guy]

Dave,
I had a similar problem with my car for several YEARS until I found my problem.
My electric fuel pump was wired to the accesory circuit. This works fine for a carburated car but an EFI engine needs fuel presure at the injectors. When you turned the key to the start position the fuel pump would stop and presure would drop. It was a miricale the thing ever started ! I did not find the problem until I put a presure guage in the gas line. I rewired the fuel pump to the ignition side of the switch (with it's own fuse) and now the car starts first time, everytime. I have kept good detailed wireing diagrams of everything so if you want I can make you a copy and send them in snail mail. Drop me a PM with your address. My car is an Everett- Morrison. When they 1st sent me the diagrams for coverting to the EFI they completly forgot to include the hot lead to the coil. Needless to say I got nowhere until that was cleared up.

Many mfgs. could overlook the fuel pump issue. On older cars it makes sense to put the pump on the accessory circuts.

My limited understanding is the computer baseline is close enough that the car should start even without the computer getting power while the car is off.

[ivebeenbit]

Originally posted by A Cobra guy


Dave,
I had a similar problem with my car for several YEARS until I found my problem.
My electric fuel pump was wired to the accesory circuit. This works fine for a carburated car but an EFI engine needs fuel presure at the injectors. When you turned the key to the start position the fuel pump would stop and presure would drop. It was a miricale the thing ever started ! I did not find the problem until I put a presure guage in the gas line. I rewired the fuel pump to the ignition side of the switch (with it's own fuse) and now the car starts first time, everytime. I have kept good detailed wireing diagrams of everything so if you want I can make you a copy and send them in snail mail. Drop me a PM with your address. My car is an Everett- Morrison. When they 1st sent me the diagrams for coverting to the EFI they completly forgot to include the hot lead to the coil. Needless to say I got nowhere until that was cleared up.

Many mfgs. could overlook the fuel pump issue. On older cars it makes sense to put the pump on the accessory circuts.

My limited understanding is the computer baseline is close enough that the car should start even without the computer getting power while the car is off.

my issue is that car starts and the idle fluctuates until is
rev the engine and then the car runs fine.shut it off--then restart
it and the idle fluctuates--i feel the ecu is losing its memory
i need to know which wire at the ecu has a constant 12v?
???
dave

[A Cobra guy]

Dave,
I got out my E-M wireing diagrams and here is what I found.
The power for the ECU goes into pin #1. That wire comes from the ECU replay. From the same pin on the relay connector another wire goes directly to the starter solenoid. This wire has a 20 guage fuseable link in it. This wire is yellow on the E-M drawings, not sure that is the origional Ford color but likely it is. (In other words this wire feeds power to the ECU rely and then continues on to the ECU itself.) This must be the hot side of the starter Solenoid.

There is another wire that feeds into the ECU relay which comes from the run position on the ignition switch.

These drawings are very detailed and go on for 3 sheets of 11x17 paper. I have a copier that will handle this size paper so I can make you a set if you would like. Drop me a PM with your address.

Just a thought. is your ECU grounded?? It probably won't run at all without a grond but I don't know.


Harvey R

[ivebeenbit]

Originally posted by A Cobra guy


Dave,
I got out my E-M wireing diagrams and here is what I found.
The power for the ECU goes into pin #1. That wire comes from the ECU replay. From the same pin on the relay connector another wire goes directly to the starter solenoid. This wire has a 20 guage fuseable link in it. This wire is yellow on the E-M drawings, not sure that is the origional Ford color but likely it is. (In other words this wire feeds power to the ECU rely and then continues on to the ECU itself.) This must be the hot side of the starter Solenoid.

There is another wire that feeds into the ECU relay which comes from the run position on the ignition switch.

These drawings are very detailed and go on for 3 sheets of 11x17 paper. I have a copier that will handle this size paper so I can make you a set if you would like. Drop me a PM with your address.

Just a thought. is your ECU grounded?? It probably won't run at all without a grond but I don't know.

.

Harvey R

that is great,i really appreciate this has been driving me crazy
i will pm my info--thanks again
dave

[A Cobra guy]

Dave,
Mailed the diagrams today, Good luck
Harvey