I have a 92 f150 that I am having issues with it won't run with out holding down the gas pedal. It blows gas out the exhaust. When you turn on the switch the fuel pump comes on and stays on it will not shut off until you cut the switch off. The check engine light is on but i can't get it to flash the codes. Any help would be appreciated.
Diamond72

 

The PCM Computer is bad and needs to be replaced.

 

check the fuel pump relay first to make sure it isn't bad.

 

The fuel pump will not come on and off with the key if the fuel pump relay is bad.

 

True dat, a bad relay can stick and allow the pump to run when the key out of the ignition. Previous owner had that problem with my 90 f150 and instead of replacing the $15 relay, he installed a switch under the wheel well that cut the power to the battery. Duh, idiot. Possible there is a problem with the TFI or distributor, it sends a signal to the PCM to tell it the engine is running and thus keep the pump running. It runs constantly when the distributor is spinning. It may be lying to the PCM when the ignition is on saying it is running when it is not. I can't remember if there is a separate sensor that tells the PCM or if it is the TFI. Anyone know?

 

Fuel pressure regular is my guess and maybe stuck injectors.

 

Oh yeah, we are not answering your first question. If it will only run when you give it gas, that sounds like the IAC (Idle air control) valve is not functioning. It allows air to bypass around the butterfly to control the idle when you are not giving it gas. Of course, going back to Subford's originals statement, you may have a bad computer. If it will not flash codes, I think that is a good indication it is bad.

 

If it won't run unless he holds down the throttle, umm, couldn't this also mean he's getting way too much fuel, and opening the throttle gives it enough air to burn it? The CEL on constantly says that the STO is definitely low, I.E. a fault. The fuel pump running non-stop with the key on, but shutting off with key off, says that output is low too. This doesn't sound good for the EEC, but on the other hand, the injectors should not be turning on if the EEC is croaked. I lean toward a malfunctioning EEC plus a shot fuel pressure regulator dumping excess fuel in the engine. OR, an error in the EEC test procedure (no offense to the tester, but been there too) which didn't initiate the KOEO. Neither KOEO nor KOER can be started if the keyswitch is already on, and the EEC is powered up. The STI must be connected to SIG RTN BEFORE the key is turned on, meaning before the EEC gets the Power ON signal to initiate the POST (Power On Self Test) and start diagnostic mode instead of run mode. Lots of folks make this mistake trying to start KOER tests after they've already started the engine. Did you connect the jumper on the DLC before or after you turned on the keyswitch? At least you're trying to get the codes.

To check the Fuel Pressure Regulator (FPR), pull the vacuum line off the nipple on the FPR and turn on the keyswitch. Don't crank the engine, and do this on a cold engine because of extreme fire hazards associated with diagnosing fuel delivery issues. If the FPR is failed, fuel will come out of the nipple. This is bad, and quite possibly the source of the raw fuel coming out the exhaust. Too much fuel, apparently WAY too much fuel in your case, cannot be burned with the amount of air that's going to come through the IAC. The fuel pump running constantly will not flood the engine if the fuel injectors are working right, and the fuel pressure regulator has not failed. Excess fuel should just simply go back to the fuel tank if the engine doesn't need it. Not running, it doesn't need ANY of it.

I don't think the injectors turn on wide open with an EEC failure. An extra ground or pinched wire can cause fuel pump relay problems. Let's take it a step at a time here and see what all we do find. Start with examining your procedure for trapping the codes. If you're positive you're testing it right, I have to go with Subford, and suggest the EEC is kaput. However, I also have to say I have a 21 year old EEC-IV that's still working fine, and another 15 year old EEC-IV that's working fine. They don't fail often. To stop the pump from running and putting more fuel in an engine that has troubles and shouldn't be run, pop the fuel pump relay out of it's socket. You'll get a code about the relay(assuming the EEC really isn't dead), but you'll know why. Check the FPR (Fuel Pressure Regulator) too. This is NOT an uncommon failure. Mine failed on my '92 and was dumping raw fuel through the engine too. It's been replaced twice since I've owned the truck. First time was complete failure, next time because I didn't like the response to vacuum.

Try your KOEO test again, and see what happens. Check the FPR for leaks. Then, come back and we can help you check the fuel pressures, etc.