KOEO tests don't show any bad codes. It fires up smooth as always but within 5 seconds it misses and dies. If I play with the throttle I can keep it running but it's missing, running rough, popping in the intake it seems. Changed to new fuel pump anf filter - has approx 32 at idle and 40 when raising the rpm. Tested Dist, changed plugs, wires, rotor, cap. No change. Seems electrical. It went from running perfectly one day to this the next.

I'm trying to do what I can to either get it to idle long enough for the scanner before I'm forced to tackle pulling the injectors. Looks like a major pita.

 

There must only be five people on this site. Appreciate what help I've got. At this rate tho it's going to take a year to fix.....

Anyone - know of a bench test for the computer?

 

Not without Ford gear. Have you considered just swapping in a junkyard ECU and seeing what happens?

 

All in all it sounds like that's the easiest thing to try next. Man,...I hate new vehicles. Give me a carb in a 1965 anything and I'll be happy.

 

Congratulations, you now get to tune and sync this!



Carbs suck. Literally.

Also, "new"??? EEC-IV is more than 20 years old now. In what possible way is that 'new'???

 

Dead Truck,

I have also hear of a bad ICM (TIF) doing same thing in your year truck.

 

Before going down the "bad computer" path have you verified spark when the problem occurs? A simple spark tester would go a long way on this one. Since the problem is reproducible you could also follow this procedure to track down the root cause: Ford Ignition Module Test. Fender Mounted Module (ICM).

Have you checked the static fuel pressure when the truck stops running?

 

I live in the sixties. Seen my business? Pontiac Engines : Rock and Roll Engineering
Type my name into YouTube and you'll see me winning Indy, without 50 hoses and lines laying all over the place and no computers!

Bruce Fulper

 

Yup. Now, make it tractable on the street to the point your elderly mother could drive it safely, with a smooth idle, street and emissions legal, and run it on the cheapest grade of pump gas. Oh, and no 'binary' throttle, either. :P

You'd quickly find, like most of the racers trying to make a good street/strip machine, that fuel injection gets a lot more attractive at that point. There are lots of guys who thought the same as you who have been showing up on the MegaSquirt forums learning to adapt EFI to their vehicles because of that.

Carb vs. EFI

I'll also put it to you this way - once you read up on EFI systems, you'll find that they're usually faster and easier to diagnose and repair than an equivalent carb system on the far more rare occasions that they require attention. I know I've spent hours and hours leaning over an engine bay trying to get a carbed vehicle to run to spec when it's having issues, and diagnosing EFI, especially EFI that's smart enough to self test and set codes, is usually infinitely easier.

Anyway, I would check the IDM as others have suggested (though I thought I remembered you writing that you'd checked for spark) or swap in another ECU. I would also suggest reading this book:

 

Oh, you're preaching to the choir. I know. Built plenty for customers. But it's the OEM snake pit under the hood that's a pita!

 

Not really. At least it's diagnosable via multimeter.

*Have* you checked for spark yet?

 

Please read previous posts. Too much too relist! THanks

 

No, I mean have you checked for spark while/when it fails? It can and should start on seven.

 

No. IT starts, smooth, 5 seconds later it misses then dies. If I play with the gas I can keep it running but it's missing and backfiring in the plenum.

 

Sounds like a fuel problem.
Backfiring is in most cases a lean fuel mixture.
Could be a bad fuel pump or fuel filter.