Problem w/ my 8.1 vortec

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Thread: Problem w/ my 8.1 vortec

  1. #1
    Walking
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    Problem w/ my 8.1 vortec

    I just bought a used Silverado with 49k miles. I love the power but over the past couple of months I have a real problem. The truck just quits. It happens on the freeway, on the road, at stop signals, at intersections etc.

    If I shut off the key and wait for about 15 seconds it starts right up. Any sooner than that and it just sits and cranks.

    I changed the plugs and wires but it didn't help. I ran it to a dealer and they said all of their diagnostics showed everything was fine. They said to bring it in when it happens again. That is kind of senseless since I would have to be there for it to happen and it would just start again anyway.

    Anybody got any ideas?

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  3. #2
    GMI Staff Member Premium Member Swahili's Avatar
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    Re: Problem w/ my 8.1 vortec

    Only idea that I have is maybe the computer. Wait to see what the tech guys who really know their stuff think (GMCSonoma, T-Type, lynch mob, Buicktech, etc..) Only reason I say computer is because we've had a problem similar to yours in the past where we took our vehicle to the dealer and were told nothing came up on the diagnostic.

    Does the truck chug like a train at all before it dies out on you?


    2000 Chevy Monte Carlo SS. Black, 3800 Series II V6, 4 speed automatic - 150,500km.

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    7.0 Liter LS7 V8 Premium Member
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    Re: Problem w/ my 8.1 vortec

    Look at the fuel pressure regualtor, make sure no gas is present at the vacuum source.

  5. #4
    Walking
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    Re: Problem w/ my 8.1 vortec

    If I am at a slower speed (20mph to 40mph) it will start chugging and I can usually feather out the accelerator to keep it going. Sometimes, like when I'm doing 70mph on the highway, it just shuts off.


    When it's running good...it's real good.

    Sonoma, how do I go about checking the fuel pressure regulator and seeing if there is gas at the vacuum source?

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    7.0 Liter LS7 V8 Premium Member
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    Re: Problem w/ my 8.1 vortec

    Jim, just pull the vacuum line off! The regulator is on the injector rail, towards the rea and the driver's side. Otherwise I suggest doing a fuel pressure check to make sure your fuel pump is OK, as that can be a little costly.

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    6.0 Liter L76 V8
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    Re: Problem w/ my 8.1 vortec

    We've had a couple come in with problems latley for similar concerns, and it turned out to be the regulator, but as Sonoma said, a pressure test is where to start. BTW the regulator looks like an acorn where Sonoma said on the left side. Like Swahili said, Lynch and T-Type could probably help you too, all these guys on this board are good.
    Last edited by Buicktech; 10-18-2005 at 08:04 PM.

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    GMI Staff Member Premium Member shadams's Avatar
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    Re: Problem w/ my 8.1 vortec

    I had a 02' 8.1 HD in about 10 times for the same thing, got to the point where we just started throwing parts on it. Fuel pump was first and most obvious, then fuel pressure regulator, but what finally fixed it was a crank position sensor. That is what controls the timing and it was intermittently inop. The bad thing about that deal is if it wont happen in the shop your S.O.L.
    "Contrary to common belief, planning is complicated and is not run by complete idiots, so you'll just have to trust that the decisions were made on good information that's not made available to you."

  9. #8
    Walking
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    Re: Problem w/ my 8.1 vortec

    i have and 02 and had the same problem and it was my crank sensor

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    Re: Problem w/ my 8.1 vortec

    Crank sensor usually.
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    7.0 Liter LS7 V8 eurohazard's Avatar
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    Re: Problem w/ my 8.1 vortec

    lol @ revival.

    Quote Originally Posted by ledfoot73 View Post
    It's simple, Toyota should recall all of the suspected vehicles and install 4 point safety harnesses, Roll cages, and maybe Hans devices.
    ^ Great quote!

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    6.0 Liter L76 V8
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    Re: Problem w/ my 8.1 vortec

    crank sensor is really common on those.
    There are no stupid questions, just stupid people.

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    Re: Problem w/ my 8.1 vortec

    I got an 8.1 in my '03 motor home that intermittently chugs between idle and 3K rpm then smooths out...
    they changed MAF, plugs / wires - no help....
    HELP
    thanks

  14. #13
    Walking
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    Re: Problem w/ my 8.1 vortec

    I have a o2 motor home and it was the 02 sensor

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