Yeah, I know, this question has been asked a thousand times. But when I did a search I never found anybody with EXACTLY the same problem so hence this question....

A friend has an early '90's Bronco with the 5.8L and approximately 100K miles. His problem is that he can't drive it as it stalls on him when it warms up. Once in a while it's on the highway but usually when idling. He has taken it to the dealer three times now and nothing has helped. The first visit, they pulled codes and said nothing was wrong, just a fluke. The second visit, they got it to stall on them. They hooked up the computer again and found nothing so their only suggestion to him was that the battery cable was corroded and the computer wasn't getting enough power to stay on. (sounded like a bunch of phooey to me but we followed their advise just in case). Needless to say, it didn't help. He again took it to the dealer. Again they got it to stall on them, hooked it to the computer, checked the fuel pressure, etc., but came up empty.

Now here's where it gets weird. Out of desperation, he decided to squirt some starting fluid into the throttle body and it started! We have tried this now everytime it stalls and it has worked. So... we now know the problem is that it's not getting any gas when it's hot, but why? Like I said, the dealer checked the fuel pressure and all was well (not to mention it's also a brand new fuel pump as well as the filters). I wouldn't think the injectors would make a difference as it runs great when cold. What else is there? Keep in mind, they have hooked it up to the computer three times and no sensors show that they aren't working. Are there sensors that the computer wouldn't test?

Any help would be appreciated.

 

This is a long shot. Has the control module been removed and tested reapeatedly. They can quit working when warm. Just a thought.

 

Hmmmm.... actually no, I don't think it has.

Oops.... wait a second.... the dealer has hooked up to it three different times now to pull codes. Wouldn't they see something had happened if it were computer related? Also, if the control module fails, wouldn't that make the 'Service Engine Soon' light shine?

One other tidbit to throw into the mix, he had his own PCM scanner hooked up to it last and after the first stall it came up with a bad IAC valve. We're going to replace it but, just wondering, could this be the culprit or do you think it's unrelated?

 

That throttle body has a line running from the radiator to it and circulates HOT WATER/COOLANT through it! I don't know if that could be it, but maybe it's contributing to the problems as there's no sensor there either. I bypassed mine, and have heard of some (Wayne where are you) that race and run ice water through it from a cool-can.
I still don't like the idea of circulating hot coolant through it but some have said in cold climes it prevents icing of the bodies. Well hope you find it soon.