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92 F-150 Idle Problem

Discussion in 'Ford Trucks' started by z400, Apr 9, 2008.

  1. z400

    z400 Member
    Messages: 82

    Guy i work with has got a 1992 Ford F-150 Nite pick up truck.
    has the 5.0 302 in it.

    He's got a big idle problem
    sucker idles at around 45mph on a flat road
    sucker is screaming in park

    he's replace the throttle positioning sensor and some other sensor

    Any ideas of what it could be?
    the idle adjustment screw on the throttle body is backed out and is
    no longer touching the bracket that the linkages hook on to.

    anyone got any ideas?
  2. Spitz

    Spitz Senior Member
    Messages: 192

    Look for a large vacuum leak first...
  3. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Check the cruise control cable. It can come out of it's holder and not let the throttle return all the way. Make sure the vacuum line is connected to the fuel pressure regulator. It's the oval thing attached to the fuel rail. It looks like an old vacuum advance on ignition distributors. When it's running pull off the vacuum line, the idle should increase if it's working. Unplug the idle air control when it's running, it should die. If not it may have some thing not letting the throttle plate return fully or a big vacuum leak or the Idle air controls bad.