My truck : 1995 F150 XLT, TWD, automatic trans, 5.0L fuel injected engine, now my problem. I live in Arizona and in the summer and only the summer when running on the front tank in the hot weather the engine feels like it is starving for gas, I lose power and engine pops through the exhaust and maybe from the manifold, then stalls. When I switch to rear tank everything is fine. When the engine cools down front fuel system goes back to normal. It doesn't do it in cool weather only when it is hot ( and Arizona get's hot ) that's why I'm thinking vapor lock. Your thoughts on this. Fuel pump was changed four years ago.

 

I doubt it. The same fuel line is used from where the two tank feed and supply lines connect down on the frame rail. Check the fuel pressure from each tank.

 

Yes check fuel PSI for both tanks.

Stay with me here for a bit.
I have a fuel injected garden tractor and when cutting the grass about half way thru, 3+ hours to cut with a 60 inch deck, it would start to surge to the point it was shut down. Let it sit for and hour and I could then finish the other half of the yard.
It was not spark as I had spark on both cly.
The only port to check psi was after the regulator and unlike on our trucks no way to see if that was the cause or the in tank pump.
Dealer told me to take an old fuel filter and cut the fittings off and use them to tee into the fuel line before the regulator for a gauge. I did it in place of the filter.

Gauge was placed where I could see it and next time out it started surging the gauge was all over the place.
Turns out with the 90*+f heat outside the pump would get hot, heating the fuel till the pump over heated and stopped working.
It got pretty hot as I felt the gas in the tank.
Yours could be doing the same thing, getting hot and starting to fail and a psi check would show this.

The other thing I would try and removing the gas cap and see if that changes anything.
If the tank vent is partly plugged it may show up only when hot and the cap removed would prove it or not.
Keep us posted what you find but I say it is the 4 year old pump.
Dave ----

 

+3 for fuel pressure check. Sounds like dying fuel pump.

 

You could just put clothes pins and aluminum foil on the fuel line and see what happens.
Something that was done back in the 60's.

 

..on carbureted vehicles. That doesn’t explain how the truck runs fine on the rear tank but not the front. If it was a vapor lock problem it would do it on both tanks.