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89 F250 460, this will test your knowledge. I can start the engine and it will run only while feathering the throttle, if you don't it will slowly die but starts right back up with no black smoke or smell. It will not idle on its own and will not stay running long enough to check for vac leaks although I did a visual check and all appeared ok. This is a conversion engine so I don't know how to read codes w/no light. I replaced the O2 sensor, EEC, and the Coil , there is no Cat because the truck is an 1986 but the motor is an 1989. The TPS seems to check out w/ no spikes while testing.
No, mine is bad also and its still running. Just hurts mileage (that im aware of). Its an expensive little bugger.
Sorry man, im out of ideas without looking and tinkering. Just double check that vacuum lines are good and closed (not broken) and that wires look ok also. Hopefully somebody else with a lot more knowledge will see this tonight and by morning you may have something.
Since the trucks has been upgraded to EFI I have to ask about what you're using for a fuel pump. If it's whatever was in it for the carbed motor then that's your problem.. it's not building enough fuel pressure, EFI needs a steady 40psi at the rail.
Yes, there is a EEC test plug. Can the code reader be purchased or rented from an Auto parts store?
I am getting another fuel pressure tester tomorrow.
Code readers for these trucks are cheap($20-30) from online vendors and not terribly expensive retail, also sometimes available for rent/loan but you'll have to check locally.