iv had my 1989 f150 for a while, and about a month ago i decided to clean the engine bay. i took out the intake manifold and the window spray/coolant resivior and hosed it down. i put it all back together, and now, whenever i turn the key, only sometimes it works. i can hear when the fuel pump goes and i know the truck will start, but sometimes it wont alot of times i have to sit there turning the key off and on over and over till i hear the fuel pump. idk what to do but its very annoying since im in the texas heat and sit in my truck without ac going. any help is appreciated

 

Check the wiring under the EEC Power relay and the Fuel pump relay.
If OK ground pin #6 of the self-test plug when the fuel pump does not come on and turn on the key. If the fuel pump runs now and not if you remove ground from pin 6 then you may have a bad computer.
This happens a lot of times when you wash the engine bay.




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thanks for the reply, il have to take a look at it some time. but its like iv got both the engine and check engine lights on, and the fuel pump only works when the check engine light is on. they both come on at the same time. could this still be the same problem?

 

Does the fuel pump run all the time the check engine light (MIL) is on?
If so you fried the computer when you washed it. Like I said above, this happens a lot of times to the computer when you wash the engine bay.

 

yeah, like when i dont see the check engine ligt, the truck wont start. how would i fix a fried computer? could i replace it?

 

Yes you need to replace it.
Take it out and take it to an auto parts place or a salvage yard and they will take the number off it and tell you if they have a replacement.
Make sure you write the number down also and keep it in a safe place.

You need to back out the 10mm bolt from its plug and wiggle the plug as you do. The bolt may get harder to turn after you start backing it out. Just wiggle the plug and the bolt will get easier to turn again.

After the plug is removed take the computer out from the drivers kick panel from inside the cab.

Computer location:


Computer plug:


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some times when im getting on the high way or going fast, they truck kinda hick ups alot. like il be driving and ittl stop, go stop, go but it doesnt feel like the transmission is slipping since the rpm goes up and down when this happens. could this also be a computer problem?

 

i found my problem! this was very unlikely but someone before me put a power chip on the computer modual. i took a look at it, and the wires were freighd and broken, causing my engine to think something other than what it should. easy fix!