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  1. #1

    gas pouring out the exhaust

    I bought a 2001 900 STX from a friend a few weeks back that have been sitting up for about a year and a half. I carried it out before the weekend of the 4th to make sure there were not problems , it ran great, on 4th of July weekend it was rode continueous no problems at all. Today I went to crank it before heading to the river, usually it cranks up very easily. It took forever to crank and when it finally did , gas is pouring out the exhaust. Any ideas??? I took the carbs apart, the float valves look good, no holes in the diaphragm, fuel return is not stopped up.

  2. #2
    Possibly the fuel tank is not venting. If this happens the tank builds pressure and forces fuel through the lines. In some cases there is enough pressure to force the needle valve off the seat and fill your cylinders. Since the tank pressure is too high to allow fuel to return, it pops off your needle valves and free flows from there. 4-stroke engines in the ATV industry see this happen occassionally so it is also very possible to happen with the marine 4-strokers as well for anyone with similar issues. If this does happen...expect a whole lot of bad to result. It thins the oil in the case enough to seize the engine...2-strokes as well if the crank gets filled. But they are more forgiving if there is oil still mixed in the fuel, a person could get lucky that way but def. no promises.

  3. #3
    I had checked the tank venting also, when it was doing this it was 101 here today, I went back outside a few minutes ago, got some long wood stem q tips to hole the slide open so i might be about to see which carb was dumping gas, guess what, it is running fine now, but makes me wonder that it might do this again.

  4. #4
    It is possible it will never do it again but it takes me at least a good summer of running before I trust something to be ok again. There really isn't much else that can make that happen at random going by how you described it. Plus with the temps you have there I would be leaning towards the venting anyway. They have a one way check valve on them which allows the tanks to vent out to the atmosphere and not allow water to backflow in. Sometimes they will seal too well and not open to allow the fumes out. I know this because it happened to me with my JS300 stand-up. At the time I had to take it in and the tech used a very small drill bit with a screwdriver styled drill to poke a little hole in it and it was never a problem again. Good luck with that and hopefully it doesn't come back.

  5. #5
    thesepaperwings's Avatar
    Join Date
    May 2007
    South East Kansas
    Don't take this is a bad way but are you sure it was gas? The 900's hold a lot of water in the exhaust. You could not have started it if it was that flooded with gas, not a chance. If you leaned back down to start then the gas would have been dry by the time it made it through the exhaust. The water in the pipe smells like fumes so maybe it was water that smelled real strong.

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