Hi folks!

I have a perplexing question here. At least, it is for me. And, I would like your advice.

I have a 1990 Ford F-150 with the 5.8 and the E4OD, 4x4.

I drive my pickup only a few times per month, otherwise it sits in it's slip and sleeps. Maybe 50 miles per month total.

Until December, all seemed fine in its little world, no obvious signs of trouble. Starting in December, I noticed that it would run fine when cold and then, after a couple minutes of running, it would act like it was out of gas, sputtering, lunging, then eventually shutting down. After a handful of minutes I could start it again and I made it straight home.

I thought there might be water in the lines, etc. So, after a couple of days, I threw some HEET in there with some fresh gas. I then drove it around for a bit, putting 35 uneventful miles on it. I thought it was problem solved.

This is in the front tank, by the way, as the rear in tank pump has failed.

So, the other day, I started her up, sounded normal. No problems at first, then, as she warmed up, she did the same routine with the lunging, the sputtering and the shutting down. For the first couple of minutes after this occurs, she may restart momentarily but then sputters and dies quickly, within 10 seconds. I left her parked.

Yesterday, I went out again, started it up and just left it sit, idling. After a couple of minutes of initial running, I can definitely hear a change in the idle process, it seemed to be "by design" that it changes something as the idle drops a couple hundred RMP's, something I have always noticed (I've owned the pickup for 13 years now, she has a touch over 100,000 miles on it) and come to expect as "normal operation". Well, while the truck was just sitting there, immediately following that shift to a lower RPM, (which I assume the ECU/ECM/computer/whatever controls) she started stuttering and dying. I could keep it going for a short time with throttle manipulation but it eventually did die again.

Has anyone ever seen/heard of this kind of activity? Is it a sign of a bad or failing in tank pump in the front tank? Something else? I wish it was something cheap and simple, like a vacuum line crack or something like that but fear that it couldn't be that.

By the way, I do not have a check engine light nor ever have had one. I do not have the OBDI reader but can get one if folks think it might read something in lieu of the dash light.

Thanks again for the advice guys, take good care out there...

Jason
Bandon, Oregon

 

It could be so you need to monitor fuel pressure at startup when this behaviour occurs.

That is also a good possibility and best way to find vacuum leaks is with a smoke tester.

The Equus 3145 is the one to get but you don't need anything but a paperclip to make the codes flash on the check engine light.