Or, he does not have spark.

Again, have you tried starter fluid in the intake? Yes, be careful, but if it is not kicking over with that, then fuel is NOT your problem.

 

So, This was a strange flashback from tuning. I went back and did find, that it does happen when you Clear the KAM (Keep Alive Memory). There are a few different ways to do this, one is a short in one of the wires to the PCM. It is NOT a permanent hard coded function.

https://eectuning.org/forums/viewtopic.php?t=6379

That being said, I am on board with the strong possibility of it being a BAD PCM.

 

Everything I have read indicates it is hard coded on the computers in these trucks, which does not make me 100% correct. I have never seen any amount of power cycling, clearing memory, etc. cause this issue on this vintage truck. This issue has happened numerous times on this forum and it has turned out to be a bad computer. The qualifier here is there was no other rigging like hard wiring the fuel pump relay, hot wiring the fuel pump, etc. In those cases obviously the computer is not at fault.

In this scenario we can agree that the most likely culprit of the OP's issue is computer related unless they come back stating there was some other wiring changes made.

Yes I have cleared the KAM on several of my OBS trucks, 1992 F350 5.8L gas engine and two 1993 Lightnings, and never experienced a continuously running fuel pump afterwards. Reading through that procedure you linked to they are removing the KAM power which may be what is killing the clock signal, but the main EEC power is still on, so that is why the fuel pump kicks on?

 

Agreed, it truly does seem to be the EEC is jacked. He is either not getting spark, or the injectors are not firing. If no spark then it could be the ICM, some carb cleaner or other starter fluid would eliminate that.
Lets see what his next move is.

FWIW, By using Binary Editor and a Quarter Horse chip, using the KAM clear procedure, The pumps will stay on, but only until the motor is started. So I do not believe that to be the issue. KAM can also be cleared if you disconnect the harness at the PCM, but this issue has been there prior to him doing that.

 

Hello again. Any idea if the computer for an 88 will work on an 87?

 

Boy you really give the least amount of info, possible, to need help getting it fixed, Have you tried starter fluid sprayed into intake track, and did it start up, when you did, or have you verified your getting spark?
what truck, motor, trans, did it have.

 

I just have to subscribe to this thread.......

 

Put the computer from an 88 in.
What have you got to lose at this point?

How much is a new computer at a reputable auto parts supplier?

 

You haven’t answered any of the questions that have been asked: do you know there is spark? Actual fuel pressure vs presence of fuel at the rail. Now you want to replace the computer with one from an ‘88 but from what I saw we don’t know what engine/trans combination is in your ‘87 or what engine/trans combination is in the ‘88. so it many or may not be better than what you have. All the gas engines were EFI in ‘88 so are you trying to put a 460 computer in a 300 powered truck or the other way around?

 

You really need to understand, that this not just a point and shoot fix it. There could be several things that are causing your truck to not start. It's called troubleshooting, not shotgunning.

We are asking questions for a reason, and you are not answering them. You need to figure out what the cause(s) is/are. It could be one simple thing, or multiple different things.

About the only thing we really know is you have a 1987 truck, we have no other info on it other than it ran when you started working on it, and now it doesn't.
As asked above, Motor size? Trans?
Have you tried priming the motor with starter fluid? Spray a small amount directly in the intake and crank it. Does it turn over?
How much pressure do you have at the fuel rail, there are several write ups on how to test that, but you will need a gauge, Not that expensive.
Let's start with this and then we can move forward.

 

I've seen pile-ups on I-20 less painful...

To the OP, newbie help-mates & anybody else:

1) These trucks have been in service 25, 30 years. There are things Ford expected them to do & things that they didn't.

2) The biggest catalog of tens of thousands of faults in several millions of trucks are here in the posts of this forum & in the minds of those who have participated the longest, not all, but quite a few.

3) When you get a clear "when this happens, it is this", particularly from some one who's been here a decade or 2, & speaks with the actual technical knowledge, you need to put obstinacy aside & get on with the repair.

YRMV

 

Come on in, the water's fine.