F150 loses power when hot.
 

Hi,

I have a 1992 F150 6 cylinder automatic with under 50k miles. On a hot
day last week (around 95) I drove around 15 miles with AC
on max and no problems and no warning lights. After sitting in the sunny parking lot for an hour or so, it started losing power gradually but quickly. I barely made it two miles before having to park it. After waiting a few minutes it would cool some, then go slowly 100 yards before dying again. I left it there overnight. The next day I was
able to drive it a half mile to a Chevy dealer with no problems.
They seemed to have no idea what was wrong with it for a couple days, but finally suggested it was a $700 fuel pump. Somehow this doesn't sound right. I drove it home about 12
miles today and had no problems, but to be careful I did not have the AC on. It had plenty of power and acceleration at the end of the trip. Whatever is wrong seems to be heat related. Has anyone else had a similar problem? Thanks

Im wondering if your temp gauge is wrong and its actually over heating, causing it to lose power and die. Ive seen it alot and i wouldnt rule it out, id check your gauge and your CTS(coolant temp. sensor).

Just an idea! You gotta start somewhere! Best of luck to you

have you pulled codes? just because you didnt see a CEL doesnt mean you dont have an issue.

this may also be your TFI module, when they get hot they will fail. If its a fuel pump you can check that yourself with a pressure gauge. Whats your timing set at? when was the rig tuned up last?

Thanks for the info. I'm not sure when it was last tuned up, but it had no known issues until the episode last week. The dealer didn't know what was wrong, nor gave me any codes. We suggested they check the EGR and fuel pressure and let it run with the AC on max a half hour or so till it got hot. I assume they finally were able to duplicate the problem. They reported the fuel pressure dropped to the 20s when the problem occurs and thought it was the fuel pump. I thought fuel pumps, fuel relay switches, and TFI modules either worked or didn't work? How could it run fine for half an hour, then die; cool off enough, then run fine again and the fuel pump be the problem? Why would it take it a half hour or more of running with the AC on max to get it hot enough to have the problem? Thanks

your first problem was taking a ford into a chevy dealer for diagnostics. either find a different shop or take it into Ford.

go to Ford Fuel Injection and pull codes yourself. we cant help you properly with out this info, chasing a ghost is costly.

It seems that you are having a very similar problem to mine. Kemical, im not very familiar with the TFI module, but if that were to be the problem, would it possibly affect the fuel pressure?

HI all Iam a newbie but what is a TFI? Have you thought about the Catylic Convertor? It was a problem for me on a Dodge Lancer once. My fuel pump on my F150 4.9 just replaced it and it would just not run when it went out or just die while driving a couple times then died so I changed it.