Several times, over the past two months, I've had my '91 F-150 (EFI 5.0L/AODE) to a local garage, then to the local Ford dealer to find out why it's wanting to stall on me. This mostly happens as I'm starting to back into where I park my truck at home, but it's also stalled at other times when starting to back up, and at one point it was starting to stall when taking off from a stop. So far, the EGR tube, right exhaust manifold, idle air control, fuel pump relay and fuel filter have been replaced, along with the coil wire when the problem persisted after the last time I had the truck to the Ford dealer.

While starting to read my current issue of Muscle Mustangs & Fast Fords magazine, for some reason I was drawn to the second page of the Summit Racing Equipment advertisement, and a throttle response calibrator by Casper's Electronics. Seeing that, I got to wondering if it's possible that my stalling problems might not have something to do with the throttle position sensor? When I restart the engine, after it stalls, I sometimes smell fuel, as if the engine had been flooded out. The only other thing I can think of would be something in the fuel injection, since if one of the fuel pumps was bad it wouldn't be flooding the engine.

At some point during the next two years, I'm planning to donate as many major components as possible from my '91 F-150 to a '57-'64 F-100, and I'll tear down the engine and rebuild it once it's out of the '91. Until then, at least until I can work on my '80 Pinto wagon this spring, my '91 F-150 is the only driver I've got, so I need to "limp it along," for a little while longer, until I've got other transportation to fall back on. If anybody has any good suggestions as to what I should look for, other than the throttle position sensor, I'd greatly appreciate them.

Matt in Indiana

 

You can check the TPS by checking voltage according to the Haynes manual. Should be 5V at WOT, not really sure what it should be if you're just trying to back up. But it's not too expensive and it's a 5 minute repair if the test in inconclusive.

-Chris

 

I would check for a vaccum leak.

 

I've been having the same thing happen to my '92, 5.0L/AODE. First thing in the morning, the truck will start to idle low then stall out. The only way to start it again is to press the gas pedal to floor, which is telling me it is stalling out. I've cleaned the IAC (which did smooth out the idle), new fuel filter, general tune up, but still have it. Pulled the codes, and got some EGR/EVT issues, which I am going to get into this weekend, as well as checking the TPS. I think it probably is the TPS, since it seems to flood out. It will only do it when its cold, after 10 mins it runs fine.

 

Thanks for the suggestions, on what the TPS reading should be, and that I should look for a vacuum leak. Also, could either of these be causing the transmission to want to down shift, from OD to 3rd, at interstate speeds? That's really killing my gas mileage, and I'd hope the transmission's not trying to go south on me, after having to have it rebuilt in September 2004.

Thanks again!

Matt in Indiana