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Thread: dying engine

  1. #1
    RC Racer
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    May 2010
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    dying engine

    i have a 3.3 that will only start with full throttle and will sit at idle with the idle screw all the way in. is the engine on its last legs or could i have troubles elsewhere like a leak? i have no history with it cause i got it off the traxxas forums.
    Breaking stuff is just part of the fun

  2. #2
    RC Turnbuckle Jr. KyLeader7's Avatar
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    What RPM range is it at when the screw is turned all the way in?? I imagine you have a problem other than piston/sleeve issues. Pull off your cooling head and see what the piston looks like. I would order a traxxas carb rebuild kit and rebuild the carb as well. Look at the crank and connecting rod after you take off the starter, and backplate. OR tear it all apart, and we'de be glad to chime in on what we may think in regards to it's looks.
    Learn by doing

  3. #3
    RC Racer
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    i just had to clean the carb before this started but i also noticed a little spitting around the high speed needle and fuel inlet.
    Breaking stuff is just part of the fun

  4. #4
    RC Champion
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    Time to rebuild the carb.. Sounds like the o ring seal on the HSN or the base is leaking.. Be very careful when removing from the carb. The plastic where the HSN goes into the carb can strip easily, you want it snug against the carb, do not over tighten this or it will strip and you need a new carb body..
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  5. #5
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Back to basics. Takes 4 things for these engines to run.
    1. Fuel
    2. Ignition source
    3. Air
    4. Compression.

    First thing I'd check is your compression. It's obvious you have ignition source and getting air. Sice you bought the engine used you need to find out what your dealing with.
    With the engine cool rotate the flywheel counterclockwise as the piston reaches the top you should feel the pinch of the piston sleeve creating resistance and making it difficult ti turn the flywheel. If you do not feel a decent amount of resistance then the compression is gone, go over the head bolts and replace the glow plug, retry.

    If you pass the compression test, clean the truck really good run a little bit of fuel through it now check for any fuel residue around the fuel tank or engine, if you find that fuel has been slung around the inside from the flywheel area the front bearing has a leak.

    Also check your fuel lines for any splits/cuts, check the o-ring on the fuel tank lid making sure that it seals.

    As far as cleaning the HSN, be very careful, the plastic housing is very easy to cross thread and/or strip. I don't think this is your problem though.
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  6. #6
    RC Racer
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    just out of curiosity how is a high speed needle set up on the carb i have two washers on ether side of the fuel intake piece. I'm going to clean the car tonight and try that to run it again to see if its spitting anywhere else. Oh and ive checked several times the compression is good its just like my revo's engine strong compression.
    Breaking stuff is just part of the fun

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