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Carb is dripping fuel

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I noticed on my ride last Saturday that my card was dripping fuel out of the black hose that comes out of the bottom of the carb. When I was riding slowly on rough terrain I would stop over a rock and it would drip 4 or 5 drips and then it would stop dripping, motor still running. I could rev the engine and it wouldn't drip. Only when I was creeping over the slick rock. Prior to this ride I changed my Main Jet to a larger 148, I moved the clip to the 5th position, and I added Jesse's Extended Fuel Screw. I don't think I messed any of it up putting it back together. Any ideas what would cause this to drip?

Here's an interesting tidbit too. I bought one of these:

http://www.rockymountainmc.com/Product_Details.atv?pid=00082489

to look cool you know. But it only allows the air to vent into the tank. So, halfway through my ride when my fuel tank was warm, I cracked the cap and there was tons of pressure built up. So could this added pressure have caused my fuel leak out of the carb? Regardless, I am going back to a hose to vent the cap, I don't think that can be good on my tank to have it expand like that.

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that thing is causing your problem. I installed one on my bike and had the same problem. the tank pressurizes as the gas fumes expand and fuel goes past the needle/seat and out the overflow.

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Another possible cause- I've noticed that whacking the throttle open quickly and repeatedly causes the accelerator pump to create pressure in the float bowl. It's just like using a plunger in your toilet. On my bike, it actually creates a siphon effect and will completely drain the tank through the carb vent if I don't break the vacuum by shutting off the petcock.

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I had the same problem and replacing the accelerator pump diaphragm was the solution. I had to replace it a couple of times over a three year period.

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