dwleo2

1992 Mustang GT. 5.0 L with minimal upgrades and stock heads.
I could easily gather codes from my old ’89 but have never been able to get them from this engine.

This has been an ongoing problem that has kept me going in circles. Several weeks ago I had a serious overheating and general steam bath under the hood. I limped home (only about 8 blocks – mostly downhill) and left it in the driveway to cool down. Once cooled, it would not start. Subsequently it has only run if I squirt gas into the intake. I have, at times doing the checklist, spark/no spark. Grounds/ intermittent grounds.
To date I have replaced the dizzy, TFI module, fuel pump relay and TPS.
Here is the tests I have done and the results:
1. Checked leads to TFI from computer. Found some anomalies and solved the spark/no spark by replacing lead from TFI #6 to EEC #16. Good strong spark.
2. Fuel pump primes when key is turned on and have full 12+v at relay.
3. Ignition switch checked
4. TFI pin 6 has ground
5. TFI pin 3 has 12v at ‘start’
6. TFI pin 4 has 12V on ‘run’
7. 0.9v on TSP
8. EEC pin 40 & 60 – no change when cranking
9. 12v at red wire for injectors
10. Fuel pressure present at schrader valve

So far everything normal but with a noid light at the injectors I get the faintest possible flash when cranking. However if I have the key on and the dizzy loosened, I can turn the dizzy and activate an injector or two and I get a much brighter flash. It also will flash bright when running after squirting.
I have a couple of grounds still to check but that’s tomorrows under car job.
The main thing is the injectors are not firing in ‘start’.
I am about at wits end.
Anybody got some ideas?

dawson1112

I don't want to speculate, as Im not that informed on all the functions on the eec, but have you checked your throttle position sensor?

I know that if you hold wot while you crank the car it will disable the injectors, usefull for getting a car to start that has flooded out.

Is it possible that your tps is sending full signal return back making your eec think its at the wot position?

88 orangepeel notch

Good advice above, and I think your on the right track with checking the grounds. They can cause a ton of problems.

You said you had fuel pressure at the rail, how much ?

It's weird that you can't pull codes, I've read on another forum that someone had the same problem with pulling codes and it turned out to be a bad ECM.

dwleo2

TPS was changed for a new one as I could not get the voltage under 3.9v.
It now reads 0.9v.
This is a multi-problematic engine.

dawson1112

I too am wondering what your fuel pressure is. Are your getting at least 35psi, with no or very little leak down? Some times the fuel pressure is enough once the car starts, but having say 29psi may not start the car. Or if the fuel pressure is leaking down it will pull air into the system and may cause it to take an extreme amount of cranking before it will start , if it starts at all.

dwleo2

at wits end (again).

Anyone have a eec for sale?

Boss_Hotrod

Check the salt and pepper shakers. There was a recall on them for the later year cars. Supposedly they dont make good contact and the fix was some short piggy back connecters. I recently took the ones off my brothers 91 and replaced them with some msd duestch connectors. He had a stumbling issue after raping the car and trying to ease back on it. Sounded like it was missing. He also had a loose ground on the injector harness which didnt help any either.

dwleo2

I read where lack of power (bat) can impair sensors and of course the eec loses memory. I also remembered that when I left the car to cool down for a couple of days, the battery was deader than disco. Only had two things left to do new eec or new battery. Battery was much cheaper so I started with that.
There you go. New battery, squirted and started and I left it for 30 mins.

Came back, turned it off and tried starting with ignition switch and .........
BAM!!! it started. Turned it off and tried again and it started. I'm not fully confident yet and will wait until tomorrow before I put all its innards back in place (and start it every few minutes or so).



In the meantime THANK YOU to all contributors who aided me in finally getting to the final root. I am still convinced this was a multiple problem with the other troublespot being the TFI and/or PIP. Once I changed them out the pond was a little less murkier.



This car is making me old and grey ......

88 orangepeel notch

Glad to hear, good luck and keep us posted.

dwleo2

Got a temporary permit today and went for a spin (full of trepidation ).

Car performed like nothing had ever happened. I think it just likes to spend my money.
Items replaced:
Distributer
Module
Coil
TPS
Ignition Switch
High Tension Lead

Nice to drive it again. All is forgiven to it.