Ok, my car has been ready to start for a week and a half now. I still don't have an injector pulse. I have a '67 Mustang with an EFI 5.0L with a single MP T70. I am using a '88-'89 California (MAF) 5.0L harness. I have spent a few hours, in multiple sessions, on the phone with a gentlemen named Jeff at Ford Racing's Tech Line. He is extremely knowlegable about the EFI harnesses and complex wiring issues. Here is what I have learned from him. The TFI module sends a signal simultaneously to two places. One to the coil to let it know when to fire, and two, to the computer to tell the computer to switch the ground on to pulse the injector. Now, in wiring the harness, there are two wires (near the EEC connector) that must be spliced into to power up the harness. A red/blue wire and red/green wire. The red/blue wire gets a 12V run only source. The red/green wire gets power in both the crank and run situations. We have confirmed the proper operation of this by probing the 12V lead on the injector plug with a DVOM and seeing that in fact it does have 12V during crank and run key positions. Next, we tested the wires between the TFI module and the actual computer connector. I probed pin 16, 36, and 56 in the computer and verified continuity with the proper wire at the TFI module. All three had continuity. Next, we made sure the computer had the proper power and ground circuits for itself. Probing pin 40, 60, 37, 57 (maybe one other - have it written down at the shop) revealed that all circuits were intact and had power and ground at the appropritate places. We thought the computer itself might be bad. I installed my computer into a known running vehicle and it ran with no problems at all. I did the same thing with the TFI module. I also checked for any expanded pins at the computer connector. One seemed slightly large but did not change anything when squeezed back together. Our next idea is something is bad in the harness. My car has not been running for approximately six months. During this time, the computer was never disconnected. The engine has been out of the car and the wiring harness has been zip tied to the fire wall. Previous to this, the car was running just fine. I also tried cranking the engine over while I wiggled the wires on the firewall to possibly discover a short/broken circuit. This was to no avail either. I don't know what to do. For some reason the computer isn't receiving the signal from the TFI module so it can pulse the injectors. This is even though the wires between the TFI module and computer are good and have continuity. I am in the process of looking for a new harness to try (hard to come by). Does anyone have any ideas to help me get this thing going? It's killing me. Thanks.

Bryan

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Do you have the main harness power relay wired in to a 12 volts while cranking and run position..?? Have you checked the injector narness to make sure that it has 12 volts while cranking ..??

Later Rob.R

 

Yes, I have. I mentioned this in the original post. I also "bypassed" the key and jumped the starter solenoid just to be sure as well.

 

Well , it seems that you have all of the power circuits covered .. The only thing now is to make sure that all of your ground circuits are grounding to complete the circuit and also make sure that the single orange wire on the injector narness is grounded also .. Is your ignition coil firing when you crank the motor ?? Also what year harness are you using ??

 

Yes, the oragne wire at the back of the injector harness is grounded (LH rear intake manifold stud). As stated, I am using an '88-'89 California MAF harness. And yes, I do have spark!

 

the dizzy signal should go to the comp , then the comp sends it back to the coil to alter timing based on load, this will also help te comp recodnize the engine position to fire the sequencal fired injectors, there should be a wire on the comp that gets this signal, do you have any thing to maesure this(a square wave meter), i would recmend a snap on vantage, i would chase this first, then check injectors for 12v constant on the hot side , this will kinda leave it to be a trigger problem with the comp!

 

THE CAR IS RUNNING!

The TPS was the problem. Thank you guys so much for your help!