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Discussion in 'Ford Trucks' started by Silverado84, Oct 27, 2001.

  1. Silverado84

    Silverado84 Junior Member
    Messages: 7

    My son has a 81 F-100 with a 4.9 L inline 6, auto trans, with a carb.
    He can't get it to stop pinging under throttle
    Any of you ford guys ever ran into this ?
  2. Big Nate's Plowing

    Big Nate's Plowing PlowSite.com Addict
    Messages: 1,266

    Sounds like you have some spark knock issues there, the distributer is advanced too far and needs to be turned back some.
  3. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    He needs to check his timing,for starters,I would set it a hair late,this will cost him a little power though.Next,is the engine running hot?a hot engine pings easier than a cooler one.Last carbon build up,it seems to be common with Fords,especially if it has a lot of stop and go driving on it.Carbon build up will make it ping,and even run lean on occasion.The only fix for this is remove head,and clean intake valves,piston tops,and head,or try seafoam top engine cleaner.Id run a few cans thru the carb,spend 20 bucks on 4 cans,it may loosen a lot of it up.
  4. thelawnguy

    thelawnguy PlowSite.com Addict
    Messages: 1,011

    Did it start pinging suddenly, as opposed to him noticing it getting worse over time? An engine which suddenly starts to ping excessively could either be overheating, or have an EGR system problem.
  5. Silverado84

    Silverado84 Junior Member
    Messages: 7

    Thanks Guys !!!!!!!
    His truck does not have an over heating problem.......... a new EGR
    valve.......... no vacume leaks..........
    Maybe a bad temp. sender????
    Isnt the timing always being "adjusted" by the E.C.M. ????
    also........... the truck has a new 02 sensor
    And yes.......the problem came on suddenly
    Thanks for all your help
    Silverado 84
  6. thelawnguy

    thelawnguy PlowSite.com Addict
    Messages: 1,011

    If its one of those electronic feedback carbs it may be running lean. Also check the voltage at the O2 to be sure its good (even tho its new).

    My strong hunch is the truck is running lean due to some carb/egr/ecm problem.