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89 F350 7.5 Runs rough

Discussion in 'Ford Trucks' started by rockin s, Dec 22, 2008.

  1. rockin s

    rockin s Junior Member
    from Wyoming
    Messages: 12

    My 7.5 runs rough at idle and sometimes just dies at idle. It runs pretty good goin down the road. I did a tune up w/plugs, wires, cap and rotor. Could it be a bad injector?
  2. rockin s

    rockin s Junior Member
    from Wyoming
    Messages: 12

    Noone has any Ideas?
  3. wahlturfcare

    wahlturfcare Senior Member
    Messages: 323

    mine was doing the same thing with the 460 and it was the air bypass valve. it would run rich and sometimes kick the check engine lite on and off. Cleaning it would help but it always came back until i changed it.
  4. rockin s

    rockin s Junior Member
    from Wyoming
    Messages: 12

    I was thinking It might be that but I didnt know how common that was, I am a Diesel guy so Im not into what the Gassers qwirks are. Thank you for the Info I wll give it a try.
    Merry Christmas.
  5. Case580M

    Case580M Senior Member
    Messages: 215

    you say injector so assume its EFI and 88 or newer?

    How many miles? Many things can be wrong with a EFI'd 460.

    shoot me a pm and can help you out over phone or by email.
  6. fordzilla1155

    fordzilla1155 Senior Member
    Messages: 127

    vac. lines dryrotted?
  7. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    I do believe you engine has pretty much the same systems my 5.8 has. Most times with EFI on a Ford Idle problems are the "Idle Air Control" or the "Throttle Position Sensor".
    You might unplug them and see if they are gunked up with stuff. Most times it's not that easy! The single model repair manuals available at part stores have check out procedures for componants. But of course, they never have problems when it's sunny and warm. I just replace them so I know they are good to go!
  8. Acmemechanic

    Acmemechanic Senior Member
    Messages: 137

    There are so Many Possibilities,Idle air Control,Rotted Vacuum Lines,Rotted JUICE CAN Vacuum Supply,Sticking EGR Valve,Bad Injector,Broken Harness To Injector,Leaking Intake Gaskets,Stuck Or Burnt Valves,Blown Brake Booster Diaphram.I Guess A Couple of Cans Of Good Carb And Choke Cleaner And Spray Around The Intake And Vac Lines With the Motor Running and Listen For any Change In Idle Or Idle Quality Woud Be a Start.