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  1. #1
    Sr. Apprentice
    Join Date
    Jul 2009
    Location
    Weatherford, TX
    Posts
    56

    Default PCM B Fuse blowing on '91 sub, 350 TBI -- PLEASE HELP

    I haven't found many helpful posts about this so I'm asking myself...what in the HELL does the PCM B fuse go to?

    I've read things about fuel pump, fuel pump relay, ecu, ignition switch, etc. No one really seems to have hit the nail on the head yet.

    My dilemma: twice in the last week my truck has randomly died while driving. Culprit: Blown PCM B Fuse. Engine still getting fire...will run for a few secs when gas is poured down TB and started. Which tells me it's fuel-pump related. That's all I know. I know others are still trying to figure this out as well.

    PLEASE HELP!!!!

    And thanks


    PS, how bad would it be for me to just put a 10A circuit breaker in the fuse slot? I've done it before with the idle/gage fuse that was blowing randomly on another truck, with no problems.
    '95 1/2 ton Suburban 4wd 350, 140K, w/ tornado and k&n filter | everything else stock

    '89 1/2 ton Suburban 2wd 350, 200+K, completely stock except 31 x10.50 tires & 40 series flowmaster

    '85 1/2 ton Suburban 2wd 350, 250+K, burnt valve :lol: , edelbrock 50 carb, comp cam, silvolite pistons, HiPerf distributor, 18" glasspacks

  2. #2
    Sr. Apprentice
    Join Date
    Jul 2009
    Location
    Weatherford, TX
    Posts
    56

    Default

    Figured I'd bump/update this one in case anyone is having similar issues...

    PCM B has to do with the fuel pump, and shuts it off if the fuse blows. In my case, there's a small short somewhere in the circuit that trips when I drive over very bumpy or gravel roads. I put a circuit breaker in, hasn't been an issue since, as the problem is never more than 1/2 second.

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