Hi all. I have a 1996 F150 with a 5.0, automatic. I have this odd problem where, if I turn the AC on, even just for a minute, a few minutes later the truck acts like it's not getting fuel and will start stalling out. The truck has dual tanks, and if I switch to the other tank, everything works fine. Also, if I let it set for about 30 minutes, it'll again run fine. It's not throwing any codes and I'm kind of at a loss for what this could be. I don't believe it's the IAC since it runs fine on the other tank. I thought it might be bad gas (the truck sits a lot) but I ruled that out after I started it up after 30 minutes, and drove it for about another 30 minutes with no problems at all. Also, this problem happen no matter which tank I'm switched to at the time.
Anyone have a thought on where I should go from here? I'm considering unplugging my battery and doing a full ECU reset to see if that helps because this just doesn't make sense for anything else.
-- Randy

 

The more we know about the truck & its history, the more-likely we can help. Click this, read the caption, and put ALL the truck's details into your signature:


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There is no "reset" - disconnecting the battery will just make the PCM forget the adaptions it has learned for the wear in your truck's engine. But it will run worse while it re-learns them over the following ~25~50 miles.

Check fuel pressure with a gauge - particularly when the symptom is present.


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Well, I put a lot of the details also in the original message. I don't think it's fuel pressure since this happens on either of the dual tanks and each has it's own fuel pump. Also the truck runs fine otherwise. If it was fuel pressure I'd think I'd have some hesitation when driving it without the A/C. The really weird part is just turning on the A/C for a minute and turning it off causes this problem to show up the next time I drop to idle. And I can switch to the other tank, get the engine revving, and switch back to the one I had it on when I messed with the A/C and it still acts up.

 

I believe there is a solenoid that kicks the idle up when the AC runs, keeping things in range of the computer. I don't have the wire diagram for your year, not sure where or part number.