Howdy all. I have a '95 f150 4.9 with 5spd manual with dual tanks. Having an issue where my truck loses fuel power when it's hot outside, happens with both tanks. Truck runs totally fine if it's parked out of the sun and only taken short distances but as soon as it gets in 85+ heat for more than 30min you have to slam the throttle down for it to accelerate at a normal pace. And even then it gets no torque/power especially in 3-5th gear, rarely even being able to get it up to 5th gear. If turned off after getting hot and trying to restart it turns over fine then sputters and shakes like it's not getting any fuel before dying. After letting it cool off it starts up and drives fine.

Replaced radiator and thermostat thinking it was a cooling issue (despite the fact that it never actually overheats) and that made no difference. Replace the d cap and rotors as well as the ignition control module with no success. Tried to replace fuel filter but one of the hoses is stuck. Thinking about switching the maf and looking at the fuel pressure regulator next but honestly have no idea what could be the issue. Took it to two mechanics who offhandedly recommended the radiator but said they didn't know (radiator obviously didn't fix it.) Any advice on what to check next or where the issue might be is greatly appreciated. Thank you!

 

IMHO, stop throwing parts at the problem and diagnose it. 1- check fuel pressure while operating in those conditions.

 

Okay thanks. That's where my frustration is, that I don't know where the issue is coming from, but it doesn't have a check engine light. I have a fuel pressure tester on hold and my plan for tomorrow is to test it. What can I learn from checking the fuel pressure? Are there other things I can check for to diagnose it? Thanks.

 

If the fuel pressure suddenly drops in the rpm zone where the trouble is occurring then it's fuel related....... fuel pump, filter, or could be a wiring issue that is causing the pump to 'fail". Next I would look underhood...specifically the TPS as underhood het will make for drivability issues. The tranny will not upshift unless it has the power to "handle it". Would also look at the ignition conrtrol module even if it is new......

 

Being a 95 it has EFI why not check for codes?
Also being EFI it would have a fuel PSI regulator.
Pull the hose to it and see if there is any fuel in the hose.
Dave ----