Help Me PKRWUD or anyone else !!!!!!!
 

I am having a problem getting my car running. It is a 1991 mustang LX 5.0. I am getting no spark, and no injector pulse. Before i found out there was no inj. pulse, i replaced the coil, and module. No luck. So then i tried another distributor, and another ECM. Still no luck. Then after i found there was no injector pulse, i was told it might be the EEC relay. When i turn the key, the relay clicks. I was then told that the relay might click and it still might be bad, because it possibly runs another circuit. I think this relay is still in working order. But i heard you were the BADAZZZ tech around here, so i am turning to you for any assistance.

Joe
Ocala, Fl
91 LX 5.0

This just recently happened on my modular...

Are you SURE its not your EEC\PCM?
That is the usual suspect. I've also seen the PCM wiring harness have a problem resulting in that sort of issue... do the usual "tap" test to see if there is intermittent connectivity somewhere in the harness around the PCM connection.

The relay could be at fault, that little sucker connects to so many systems its like a darn Christmas tree. I feel your pain brother, as I know that clicking sound well... ;)

How would i go about doing this tap test. Where should i start, and what should i do. I am clueless !!!

"Tap" Test: Tap on whatever part you think is messing up and see if the problem clears for a second or two :p

Is there still no spark, or just no injector pulse?

Also, do you have a DMM (Digital MultiMeter)?

Check the two large engine harness connections (one black one white) on the firewall side of your intake for good contact. Pull them apart, inspect and clean them. Also, make sure your chassis to engine grounds have not corroded or come lose. Dose your fuel pump still prime when you turn the key? If so, sounds like a wiring prob in the engine bay. I assume it cranks but dose not start? When did this happen? after a mod? or just out of the blue? :confused:

The problem just happened right out of the blue. It sounded like it ran out of gas. there is no inj. pulse, nor any spark.The 2 large connectors you are talking about, are those the 10 pin connectors? I have noticed on a couple friends mustangs, that they have 4 of them. The engine ground seems to be good, but i am going to run another one, just to be safe.

Joe

Do you have a DMM, and do you know how to backprobe the TPS in order to test it while it's hooked up?

Yes i have a DMM. and No i dont know how to back probe the TPS

Joe

It is possible that the power feed to the TPS is shorted, creating a WOT signal to be generated and read by the ECM. This would put it into clear-flood mode, which would kill the injector pulse. I need for you to rule this out first, which is why you need to check your TPS idle setting.

To check the TPS, you will need to access the green wire while the TPS is connected to the harness. You can try to backprobe it with a DMM lead or pierce the wire with a very small safety pin. Attach the DMM pos lead to the pin (or backprobe), and the DMM neg lead to good engine ground. Turn the key "on". Set your DMM to 20vdc scale. With the throttle closed, at it's idle position, what does the DMM read?