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1990 3500 454 problem

Discussion in 'Chevy Trucks' started by CSC Contracting, Nov 8, 2010.

  1. CSC Contracting

    CSC Contracting Senior Member
    Messages: 105

    I have a 1991 GMC 3500 with the 454 TBI. It is runninig rough when going down the road it starts to surge really bad the tack starts jumping all over the place and if I jump on it It will bogg down a little and backfire through the carb. Looking for some ideas on what it might be I was thinking fuel filter or distributor. Thanks for any help.
  2. littlejohns77

    littlejohns77 Junior Member
    Messages: 4

    I had a 88 K3500 With the 7.4 and it did he same thing last winter it was the distributor . When I took off the cap you could see the moisture in there new reman $100 and all was good Good luck
  3. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    I've heard about intake vacuum leaks, but that may have been on a newer FI motor. You could try spraying some WD40 or other petroleum based spray while its running to rule out a vacuum leak. Otherwise I'd guess distributor also.