'91 f150 I6 4.9 2WD with about 137k on it. Last week, out of the blue the truck stalled as I was getting home. It would restart, but the fuel pump whine sounded weak, and the engine would die. I let it sit for a bit, and started it up, with a stronger sounding fuel pump whine, but it died again, just not as quickly as my other restarts. I left the truck until morning, started it right up with no problems, and drove it to work 22 miles. At the end of the day, not even a block out of the parking lot at work it stalled at an intersection. I was able to restart the truck, and only after keeping my foot on the gas kept the truck running to reach home(I must also add that when on the freeway, I didn't have to do this, only on the lower speed surface streets). I did some research online and in the Haynes, replaced the thermostat, coolant temperature sensor and the intake air temp sensor. The truck still stalls, but it does not seem to do so as quickly - but I'm willing to admit that might just be me hoping for good news. At this point, I am at the end of my rope, and brought the truck to the shop. They have had the truck for three days, and cannot find the problem - the biggest issue is that there does not appear to be a pattern. The truck will run fine, and then just cut out. The time intervals vary, and there is no warning from the truck, although if it is idling it will give a small sputter or two and then just quietly go to sleep. There are no codes. If I had to describe it at all, it is *exactly* like using the inertia switch to shut off the fuel pressure.

 

When was the last time you replaced the fuel filter?

 

Does your truck have the fuel pump on the frame fed by a pump in the tanks? Is it single or dual tank? If it's dual tank, does it do it on both tanks? If I were you, I'd invest in a fuel pressure guage and drive the truck until it acts up. When it stalls check to see if it has fuel pressure or not. It's a little puzzling that it doesn't stall on the highway if it is a fuel pump issue.

 

About two years ago... . I did think about that, but would that be intermittent?

 

It's a dual-tank. I think the pumps are in the tank, to be honest I have never looked. If the pumps were failing, wouldn't the truck run roughly?