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We have a '90 F150 302 that has no spark. With the "timing spout" removed the truck will start and run. Once the "timing spout" is re-attached the truck kills instantly. No spark.
What could this be?
I will try to look at the wiring diagram in my manual tonight.
I would GUESS that it either has to be a bad ignition module, bad pickup in the distributor, or defect in the wiring between the two.
A remote possiblity is the ECM. I have studied the schematic at length, but can not remember how it all fits together.
Thanks for taking the time to look. We've replaced the ignition module and really wondered were else to look. We have plenty of fuel and this problem is really baffeling us.
Steve, I looked in my 87-93 F150 Chiltons and the skimpy wiring diagram in there does not even show the spout connector.
So I pulled out my 89-93 Mustang Chiltons and looked through the 22 pages of diagrams (for each year). It turns out that the spout connector does not "short" anything. It simply attaches the TFI output (a sample of the output) to the ECM when inserted.
So I still am under the assumption that (because you have replaced the TFI module) it is either a defect in the harness or a defective ECM. In looking at the schematic, I no longer think it could be in the distributor pickup. (Wouldn't be the first time if I were wrong).
I have all the Ford CD's for cars and trucks from 92 through 2001. I will search the truck CD to see if the 92 has any more info.
UPDATE: I checked the CD for 92 and it verified what I learned from reanding the car chiltons.
The Spark out (spout) signal goes to pin 36 on the ecm. It is pink.
Here's what I would do. Caveat - If you don't feel comfortable doing this, then don't.
Disconnect the negative terminal on the battery.
Disconnect the ecm harness at the ecm.
Disconnect the cable from the TFI module at the distributor? or is it on the firewall? In 92 it was on the firewall.
Make a "short" test on the pink wire with an ohmmeter. Check for continuity to ground. You can pull the spout plug and check it there - both diretions. You should have infinite resistance. If you have 0 or any reading on the ohmmeter, your wiring has a short.
Make sure you do not make a continuity check with either the ecm or tfi module connected - it could damage them.
Throughly check the wiring for a pinched or scraped area that would cause it to short the signal to ground.
Did the symptoms appear after some maintenance, or just suddenly?
The symptoms began intermittently ie the truck would just die instantly going down the road. Then, restart after a while. Well, intermittent became permanent.
I looked at the wiring to my spout on my 88 F150. Instead of pink like the information I gave you said, it is white with blue stripe.
Anyway, I don't know what else to tell you to try. Again, I would try and eliminate the wiring harness, and if no fault found there, it points to the ecm. It would be good if you could "borrow" an ecm to test with, or maybe find a good used one at a salvage yard.