hey guys. truck won;t start unless you shoot ether in throttle body, fuel-pump replaced with new. runs constantly while key is on. truck cuts out like its not getting gas try to rev full throttle light acceleration is ok unless you wott it. has new coil pickup, ignition module fuel pressure regulator, both pump relays cleaned tested ok. distributor overhauled. some up down end-play on shaft but not back and forth. Note: fwd gas-tank rusted off and not there, wires are tied up. no fuel selector valve. does the computer have to see two gas-tanks.

 

Classic symptoms of a bad computer (PCM) in bold above, especially the fuel pump running constantly as described. Remove the PCM, open it up then look for signs of moisture damage and/or leaking capacitors. Regardless of what you find I can just about guarantee you need a new PCM.

 

PCM thats what i thought!! my dad thinks its a bad sensor, It tries to idle too then goes 1200rpm stays there. as soon as you mash the gas woooommm and it kills then you let up. it comes back on. No CAT either, but it should still rev up? PCM is under driver kick-pannel right? also what can you put into for a swap pcm, can it come from any year 1990-1995 truck with 5.8 and auto trans? what about the E series vans? i believe i have the E40D trans since i have overdrive. i was thinking of picking one PCM from the junkyard. Is it cheap to rebuild the PCM unit? I might get some radio-shack transistors and stuff to solder into the failed parts on the board?

 

Also... I have a good working f250 4x4 5.8 auto with overdrive that i am running to and from work. would it be smart to put the good PCM into the one with the bad PCM and test to see what it does? could it short out and blow something else and brick my other PCM that i need for the good truck or should i put the bad PCM into the good truck to test that?

 

The PCM is located behind the driver side kick panel and it is removed from inside the cab on your model year truck. You can try swapping in the PCM from your F250 (assuming 1988 to 1994), your existing truck with OD transmission (E4OD) and 5.8L engine should work fine with the temporary donor PCM. It is very rare to cause an issue by doing so.

 

It tries to idle too then goes 1200rpm stays there. as soon as you mash the gas woooommm and it kills then you let up.

 

My 91 did exact same thing and it was the PCM. I messed around with a few other things then bit the bullet and bought one....all has been good since.

 

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how do you add a picture? i have the PCM opened up

 

I want to buy a new one but not sure what one works with the truck from autozone. here is my PCM numbers FOTF-12A650-BPA, how do you choose a new one does it have to have the same numbers?

 

You should match the numbers as close as you can.

FOTF-12A650-BPA is the engineering number for the PCM. Some vendors use the Service Number, which I do not have at hand. Based on the number you listed it crosses to a Standard Motor Products part number of EM825.

EM825 is listed as fitting these models:

Ford E-150 Econoline (91-90)
Ford E-150 Econoline Club Wagon (91-90)
Ford E-250 Econoline (91-90)
Ford E-250 Econoline Club Wagon (91-90)
Ford E-350 Econoline (91-90)
Ford E-350 Econoline Club Wagon (91-90)
Ford F-150 (91-90)
Ford F-250 (91-90)
Ford F-350 (91-90)

 

ok. its my rust-bucket rat-rod truck... floors and cab shottt big time but its a plow truck. how do you post pictures in a thread?!? not able to figure out. anyways, could i just pluck one from any one of those vehicles in the bone yard or should i buy one from napa autoparts for $150? Ford says that i would have to have it programmed to run in my truck is that true or can you just plug in and drive it like that. also, note: fwd fuel tank rusted off the truck. does that need to be present for the computer to turn the rear pump off and allow the engine to run? they took the fuel sel switch out and have the fuel sender wires tied to the frame. two lines going to and from the rear tank to the front of engine. does anyone have a pix of the fuel select valve and where it mounts?

 

If you are not a paid member you can place your pictures on a free site such as Photobucket or SuperMotors. Then you can post them here using the Insert Image tool when posting or copying and pasting the image tags from those sites. These tags begin and end with a bracketed img forum code.


There is no programming for a replacement PCM on these trucks. If you find a junkyard PCM make sure it matches the numbers you previously listed for best results. The list of vehicles that PCM fits came from the Standard Motors product site. I do find them to very fairly accurate.

The PCM does not have to see both rear and front tanks to work, it's either one or the other. The tank select switch that was on the truck only controls the electrical path to the selected tank.

Your truck should not have a selector valve on the frame rail like the '84 to '89 model gas engine trucks. Each tank has it's own high pressure fuel pump inside. Each Fuel Delivery Module has a set of internal check valves that block fuel from flowing into the non-selected tank.

 

 

I think that resistor may be bad?!?! And see where the PCM got hot?