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85 F250 stumbles at under load

Discussion in 'Ford Trucks' started by rockcrusher4x4, Nov 17, 2003.

  1. rockcrusher4x4

    rockcrusher4x4 Member
    Messages: 32

    I tried the search found nothing to match!
    85 F250 w/ 351 windsor motor with TFI ignition system
    when the truck warms up, and I take the truck up to 3000rpms in gear it will stumble or start missing, if I push in the clutch and rev it up it doesn't do it. I have rebuilt the carb, replaced (Jan 2003) Plugs, wires, Cap, & rotor. Have checked the timing, ok, Have checked everything I can think of and everything everyone else has thought of and nothing. Is it possible that the stuff I replaced in Jan, went bad?
    Thanks in advance!
  2. edshipp19

    edshipp19 Senior Member
    Messages: 147

    could it be the cat converter your symptoms sound like what was happening when the cat went bad on my chevy blazer with a 350

    CARDOCTOR PlowSite.com Addict
    Messages: 1,312

    will it act up if you load it up in gear
    could be a bad coil or ive had distributor do the same thing
    if thats the case replace the distributor and the module

  4. meyer&western

    meyer&western Junior Member
    from 45308
    Messages: 12

    truck prob

    had one do that to me and it was the pick up coil
  5. rockcrusher4x4

    rockcrusher4x4 Member
    Messages: 32

    Thanks for the replies. I replaced the wires yesterday, had the coil tested (ok) but still does it. I am going to replace the plugs this weekend hopefully that solves the problem. If I take it above 3000rpms in gear it misses, (stumbles) if I shift into neutral and rev it up above 3000rpms it doesn't do it, just under load of driving.
  6. Plow Meister

    Plow Meister PlowSite.com Addict
    Messages: 1,174

    I would agree with the cat conv theory. Go to Auto Zone and ask to have the computer checked for codes. They will do it for free. Ask to check if the o2 sensor is working properly. Lots of times when the cat is going south the o2 sensor will make the truck run lean.
  7. Snowtraxx

    Snowtraxx Junior Member
    Messages: 5

    When under a load the engine is going to be drawing more air and fuel to it. I would check the folowing, choke sticking, carb base gasket leak, vacuum leak, poor fuel supply...weak pump(rare on mech. pump but have seen it), clogged fuel filter, float level. Check the exaust via the old paper trick...this has actuall bailed me out before...with truck at idle hold a sheet of plain paper just behind the tail pipe, the paper should not flutter back and forth, if it does a vacuum leak or restriction may be around. Also can check exaust by temp(is it really hot before the cat but not so hot after it??? Good luck, hope this helps and doesn't hinder.