1994 2WD SWB Ford F150 FI 6 cyl Dual Fuel Tank. While pulling trailer on 200 mile trip started to miss about 20 miles after switching to the Front Tank, then got Check Engine Light on and off several times for over 10 miles. Thought the engine might quit, and switched to Rear Tank (which fortunately had a little gas in it) and solved problem. While stopped with key on, I can hear fuel pump on Rear Tank ok but on Front Tank it is much louder and more of a continous buzzing noise. Had AutoZone check codes, but no codes registered. Both tanks were filled from the same station that morning and had also been filled from same station over several previous weeks. Sounds like fuel pump is bad in Front Tank to me, but there is also a selector switch, a pressure regulator (I think) and some relays in the circuit. I can use a VOM but will have to buy a pressure gauge if I need to check the fuel pump delivery pressure.Any assistance sincerely appreciated.

One of the easiest ways to tell if a Ford fuel pump is dying, is that they get louder as they die. It sounds to me like the in tank pump is on it's last leg, it operates, but does not supply enough fuel. That can cause a CEL, low power, and stalling.

Sounds like the fuel pump is giving up the ghost. Judging by the year I'm sure you have some miles on it and more than likely it's never been replaced before. I had a rear fuel pump go out on my 92' while pulling a trailer. Loss of power and rough idle when on rear fuel pump because pressure was not up to specs.

Try checking the fuel pressure while on the main tank and compare it to the rear. Chances are you'll have to shovel out $200.00+ for a new fuel pump. Not to mention the fun you'll have getting the old one out and installing the new one.