I have a 1991 ford f-150 that just died a few days ago. when i turn the key to run the fuel pump doesnt come on. if i jump the relay the pump comes on. when i jump the relay I get fuel pressure to the fuel rail but the truck still wont start. I checked the inertia swith by the clutch petal and it is fine. I changed the fuel filter. the truck has dual tank and both fuel pumps work if I jump the relay. This is driving me crazy!!!!! I dont know much about fuel injection. It seems to me that the computer must be telling the pump not to come on. even with pressure at the fuel rail the gas cant get thru the injectors. If anyone has any ideas I would realy appreciate it
Remember the switch only gets power for 1 second when u turn the key on, the common problem is the ignition starter switch comes apart, it is located at top of the steering column near the bottom, drop the column down (2 nuts) and inspect the switch for separation.
Lets cut right thru the chase and go to the heart of the matter. what you most likely need is a new ecm which is the brain computer that tells everything in the motor what to do and you may have some corrosion on the ecm connectors that run to the wiring harness which in turn could effect your direct connection to the ecm's ability to communicate to the fuel system.
Follow the cable from the positive on the battery down to the solenoid, there will be 2 posts and the cable is connected to 1 of them. touch the metal part of a screwdriver to both posts and the truck should start then.
Yeah...and you could just saw the entire front of the vehicle right off and replace everything as a unit!!! Follow emission wizzes (sp?) suggestions...Ive read his stuff and he's pretty good with problems like yours!!!
I'm gone...TG
You might have done this,but change the relay,the computer is detecting theft,and shuting down to keep the truck from starting,even if you use the key,the computer isnt receiving information from the relay to get the "all okay" to continue.
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yes I replaced the relay and the pump still wont come on.
I checked the inertia switch and it is not getting power. The truck doesnt run at all not while cranking or when i let the key off.
the only way the fuel pump will come on is if I jump the relay.
i checked the switch in the column and it looks fine I also checked the inertia switch again and it doesnt get power for 1 sec when i turn the key on
have you checked the connector to the inertia switch to make sure it isn't burned, make sure you have power in and out of the switch, also verify the ignition switch is good, the computer is bypassed during cranking so it sould run a few seconds after you let up on the cranking of the engine.
Is the relay good? ...often it not only turns pump on but tells the computer the pump is on so that other stuff will work.(just a thought)
have u replaced the relay?
what if the relay trips
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