Working on a 92 EFI F150

I believe it is an early 92 model because when the parts guy looked up the intake gasket kit for a 92 the egr gasket was incorrect but was correct for a 91 ( correct me if i am wrong)

Engine barely ran, with huge miss

Rats chewed cylinder number 3 and 7 injector wires

After rewiring injectors with new wire clips the motor still did not run except at full and half throttle

Pulled plugs #'s 1,4,5,8 were dry and slightly carboned up (normal burn) #'s 2,3,6,7 were clear clean fuely and (not burning)

Ran a compression test on all cylinders and got 135psi on all 8

Replaced distributor upper and lower cap and each cylinder is receiving ignition (broke it in the plenum removal process)

after removing all spark plugs I noticed large amounts of fuel coming out of the middle four cylinders ( # 2,3,6,7)when spinning it over with ignition on. ( large drops hitting the fender wells). So I unplugged the injectors and spun the motor over again with ignition on, and there was no fuel coming out.

So i concluded that the injectors weren't hung but the computer was telling those plugs to open for too long (ie full throttle.)

Tried disconnecting the battery and resetting the system, however the same result occurred

What do i do now?

Any help will be greatly appreciated. Ive already been paid too much for my time on this job and need to fix as soon as possible.

 

Sounds like the white wire circuit #556 is shorted to ground or is grounded in the computer.

 

How can I find this white wire circuit? Is this the white wires that are wired into the injector plugs? Are the middle 4 cylinders wired together? Obviously if it is in the computer then the computer needs to be replaced but first I need to check for faulty grounding (a short). But where?

I will check online to figure out what white wire circuit #556 is. I don't have any books or manuals.

Any help is greatly appreciated

 

Yes it is.

Yes they are.

I would think it would be a wire shorted to ground or to a ground wire.
Could be a shorted transistor but not likely but it has happened.

A 1995 diagrams but should be close to what you have:

/

 

Extremely helpful. I will look into this Monday when I am around the truck.
Too bad I will probably have to pull the plenum again to see the bundle of wires.
Still curious as to what caused this mess in the first place. The rat, who I found too be living in the hood, chewed up 2 injector wires and and 3 vacuum lines.. why isn't it as simple as reconnect the wires and lines and go...
Guess I missed a short in the wiring the rat got to.. although I've been up and down the wiring. I don't see how the computer or a transistor could go bad all the sudden.
But this is how it always goes.
If it was easy everyone would be a mechanic

 

Have you pulled the codes?

 

No i have not. I will have to read up on how to do that again