460 Stalls Intermittently, sometimes won't start.
 

Hi everyone.

This is a bit of a story, but I need to describe as best I can since I can't find any other problem on these forums that indicate the same problem as mine.

I have a 1988 F-250 460 EFI and this summer it started acting up a little. Every now and then the engine just dies, then instantly comes back to life. It does it when I'm driving under load or no load, warm or cold. It dies for about 1 second then comes back to life. Occasionally it will not start either, warm or cold. Then after waiting a bit it starts right up and runs fine.

When it has not wanted to start I could not smell any gas odors so I presume that it could possibly be one of my fuel pumps starting to go (I say this because last year I had my ECT sensor fail and when it was warm and hard to start the fuel smell was overwhelming). I did manage to have it not want to start and was able to switch between forward and rear tanks, and that made no difference so I can eliminate the tank pumps. That would only leave the main pressure pump. But of course like any intermittent problem it never happens when I'm ready to troubleshoot.

I have placed the jumper on the connector under the hood to turn on the fuel pumps and I cannot find any problem with the relay or pumps or inertia switch. I tried to simulate the problem, bashing and wiggling anything I could, but everything seemed fine. So I wasn't going to just change the fuel pump quite yet.

The last time this problem happened I was driving down a bit of a hill, coasting down without the accelerator pressed, then suddenly it died and of course came back to life a second or two later, but when it did come back to life there was a back fire. There had never been a back fire until now, but every other time it happened I had been pressing the accelerator to some degree. Now I think this sheds a different light on it. If it were a fuel starvation problem there wouldn't be a back fire, right? Maybe it's an ignition or spark problem??

So was I chasing the wrong thing in initially thinking it was a fuel issue since I couldn't smell fuel when it didn't start before, or what?? This is so frustrating. It happens frequently enough to be a concern, but infrequently enough that I can't troubleshoot it.

So realistically the only time I can troubleshoot it is when it doesn't want to start. I don't really want to arbitrarily just start replacing components hoping that I might get it eventially. I would like to get a proper troubleshooting plan together and I'm hoping than all you wise folks out there can lend some insight into this problem.

Now my last problem is that this truck is on an island, summer use only, barge/boat access only so I won't be able to do anything for a couple more months. Just hoping to gain some insight and make a troubleshooting plan.

Thanks,
Steve

P.S. there are no engine lights with this problem.

bump, anybody?

You can have stored codes or fail the KOEO tests without having a Check Engine Light on. Start with codes, it may lead you to the right place.

On the other hand it is going to be difficult to diagnose when the problem is so intermittent. The root cause could be anything from a bad battery cable/connection, a faulty Ignition Control Module, wiring to the the same or to the coil, a bad coil, etc.

Check the relay plugs real close....Did a good bump cause it to stumble?

Thanks for the reply's guys. I talked to some mechanics at my work and they both suspect it to be my ignition control module. Apparently they are notorious on the distributor mounted units. I will buy one and have it ready for when it happens again.

I also found a real handy troubleshooting guide with regards to the engine ignition system here:

Part 1 -Testing the Ford Ignition Control Module. Distributor Mounted ICM.