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nowires

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So here is the problem
93, F 150, 5.8 with Auto trans

Times are tight and generousuty is high

So the motor turns over and there is no spark. I now have this POS in the shop after the person tried to fix it for a couple months

So acording to him the ICM and coil have been changed. I have not dug into this hard yet. but just looking for some tricks for trouble shooting




Ow ya and the fuel pumps are not triggering
I have checked the fuses and relays ( no clicky on the fuel relay )

I did pull the selector switch and test that. All good there. I did energize the fuel pumps from there with a piecr of wire and now I can get then to run. ^% PSI when tested there



Please no jokes about it is a ford. This is a random act of kindness and I really want this to get fixed
 
What are the trouble codes?............could be as simple as crank position sensor....If there's no spark nor fuel pump it's because the computer isn't telling them to turn on due to the real problem. Also there should be an inertia switch which may need to be reset...
 
If it's got a factory alarm system it could be having an issue brain won't let the feul pump or coil fire. Might need to trick the alarm system some how.
 
Hi All:

I dunno Charlie, but 6 PSI seems rather low for a FI system.

Regards,

Alan
 
So after tonight and lots of looking around. Here is where we are after tonight. Still no spark

the fuel system checks out OK except for the ground leg on the fuel relay ( 85 ) I think or 86. Somehow the relay is not grounding. But I suspect that it has something to do with the ECM and no spark in the motor. I think that there is a fail safe that if (no spark ) the fuel pump will not turn on


So now we are chasing a no spark problem :cheer:

Anyone got a wire diagram for it
 
nowires said:
So after tonight and lots of looking around. Here is where we are after tonight. Still no spark

the fuel system checks out OK except for the ground leg on the fuel relay ( 85 ) I think or 86. Somehow the relay is not grounding. But I suspect that it has something to do with the ECM and no spark in the motor. I think that there is a fail safe that if (no spark ) the fuel pump will not turn on


So now we are chasing a no spark problem :cheer:

Anyone got a wire diagram for it
Click to expand...

The ground circuit is supplied by the PCM. You're chasing ghosts.
 
Binder said:
The ground circuit is supplied by the PCM. You're chasing ghosts.
Click to expand...

But if the PCM doesn't see spark it won't fire the fuel pump

you are right I am chasing gosts. But I think because people have worked on this that didn't know crap I have to take all into account.
Am I getting a signal from the distributor?
Is the coil good?

Start with the basics and go from there

I just have to rule out everything that they touched before I proceed to the next step. The fuel pump was a big concern to me, it just should of worked. But thanks to Keven and some time on the phone we knocked that one out. :awesomework:
 
Wouldn't completely rule out the PCM, but it is in my experience extremely rare that an early 90's Ford PCM fails...
 
nowires said:
But if the PCM doesn't see spark it won't fire the fuel pump
Click to expand...
The PCM never "sees" spark it tells the system to spark or not to spark.


nowires said:
Am I getting a signal from the distributor?:
Click to expand...
Again there's no signal "from" the distributor so to speak. The PCM does know however if the distributor circuit is open. When that happens there will be a trouble code.
nowires said:
Is the coil good?:
Click to expand...
Could be bad. So could many other things.


nowires said:
Start with the basics and go from there?
Click to expand...
First step for the basics is check the trouble codes!


nowires said:
I just have to rule out everything that they touched before I proceed to the next step. The fuel pump was a big concern to me, it just should of worked. But thanks to Keven and some time on the phone we knocked that one out. :awesomework:
Click to expand...
I understand wanting to rule out everything touched before. The symptoms you describe, no fuel pump and no spark are only connected in that they're both commanded by the PCM. Yes both could have gone out independantly of each other and at the same time but it's very unlikely. Also as Kevin posted it's very unlikely the PCM went out. This tells us the PCM isn't telling the system to spark or ground the fuel pump for some reason. 99.9% chance that if the PCM is shutting down it's also sending a trouble code to explain why.:;
 
Charlie I wouldn't have even posted in this thread except that I recognize those symptoms as a classic shut down PCM. Typically guys will go chasing ghosts when this happens and end up replacing a fuel pump and distributor only to find later it was a easy fix elsewhere.........After they chase down the distributor being installed wrong when they "fixed it"..........
Good luck Charlie.:awesomework:
 
The inertia switch only cuts fuel. Also I fully agree on checking codes. Obd1 systems are slow, there may not be a cel but is a stored code
 
You are right Rick I have to get the codes. I just don't have a code reader for that rig. So I have to wait till I go down the hill to get one

Everything is leaning towards the PCM but they worked on the distributor and so I want to dig in and see what is going on. From what we tested last night, the yellow wire leaving the coil is if tested with a test light suppost to get brighter. It gets dimmer when you turn the key to run. I don't know what the yellow wire does.

But for now the truck has a warm place in the shop and I will keep plugging away on it
As far as the fuel system I did jumper it at the test port and it checks out good.

Thanks for all the input. I just needed to get my truck ready for tomorrow and then I can focus more energy towards this
 
OK so here we are now

NO codes and have checked the coil and everything but the distributor and the PCM. ECC was replaced and checked it for ground


Any other points that I should look at before looking for a PCM
 

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