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Problems with 92 350 TBI

Discussion in 'The Garage' started by Mr.Vic, Dec 23, 2006.

  1. Mr.Vic

    Mr.Vic Registered Member

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    Hey everyone. i'm a noobie on the site and to fixing diagnosing problems on my 92 chevy. the motor problems recently are: lacking in power when I go heavy on the throttle it will bog down sounds like it is miss-firing, shoots some blue smoke out the tail pipe, sputters and backfires. when turn the truck off after driving for a while it smells like burning plastic... kinda goes through oil like i do beer on the weekends..

    recently replaced the cat and muffler with a high flow walker unit and a flowmaster muffler, plugs and some filters. i have not had this truck for long and its been causing me lots of greif! going to check the vacume lines and do a compression test this weekend. my buddy says it could be the timing chain is shot and possibly cam lobes are worn out causing the lack of power, blue smoke and miss fire.. makes sense but any other ideas as to what it could be. the check engine light doesn't come on and i don't have a code reader unit to see if its throwing any codes either. the odo has 128,00 kms on it but i think the motor was swapped in or the previous owner got a fan shroud from a 4.3 chev truck cause that is what the sticker says.. ie maybe the dumby who swapped in the motor forgot to change the ecu? f*uck i hope not..

    thanks for reading and your input.. if it doesn't make sense its cause of the vodka i been drinking all day :rolleyes:
     
  2. Jason4x4

    Jason4x4 1/2 ton status

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    Blue smoke is burning oil, check and make sure your pcv isn't stuck, otherwise you probably have some worn out guide seals, or piston rings.
     
  3. Mr.Vic

    Mr.Vic Registered Member

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    thanks Jason, pcv is brand new.. hoping the rings aren't shot, still haven't gotten to doing the compression test and checking the vacum lines. going to do those and put in a new fuel filter this weekend, also will check the timing too.
     
  4. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Vic, I'd start by looking at the basic mechanical condition of your engine. Almost sounds to me like someone pulled the stock 4.3L, and dropped in a tired, worn out 350 to replace it.

    No EFI system will cause your engine to burn oil, and if you arn't getting any check engine codes (and your check engine light isn't burnt out) I'd assume the TBI system is doing it's thing correctly.

    As far as the lack of power goes, the timing on those engines is very conservative, try setting the base timing to 5 degrees before top dead center, instead of the stock 0. To do this, you need to pull the cover to the upper left of the engine off, and look for the single weatherpack connector that has the brown wire with the black stripe going through it. Unhook that, and use a timing light to set the timing to 5 degrees BTDC, then hook the connector back up when you finish.

    Again, check your compression, both wet and dry, and make sure your valve seals arn't shot. I'm guessing that you probally just have a really worn out 350 between your frame rails =/
     
  5. K5Jimmy

    K5Jimmy 1/2 ton status

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    Didn't see Wires on the list of parts you replaced...

    Mine did the same thing you described and it turned out to be a bad wire...I looked at them as I replaced the plugs and they seemed just fine...no marks, no brittle spots or discoloration,etc...I had replaced the cap and rotor,etc....it ran fine as long as I feather footed it and stayed under 45 or so...load it up and it went to siht..

    Wires are cheap and easy.. may be worth a shot if you haven't done it already.
     
  6. loafer

    loafer 1/2 ton status

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    Whenever my old K5 with 350 TBI used to bog down under load and loose power it was always a plugged fuel filter. (for some reason I had a problem of getting mud in the tank:D )

    A plugged fuel filter should not cause blue smoke though.
     
  7. Mr.Vic

    Mr.Vic Registered Member

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    thanks for the replies everyone. I have not replaced the wires yet so i will get some new wires and put them on when i do the rest.

    SierraClassic - thanks for the tip on settign the timing, i will do that.

    i will post an update once i get this stuff done and have taken the truck out for a drive.

    thanks again for the tips and help !!

    Cheers,
    Vic
     

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