B&S V-Twin Carborator

I have carburetor "issues" on my B&S V-Twin 12 HP generator engine. The engine has less than 20 hours on it... so I'm convinced it doesn't need a rebuild kit.
I'm sure that the gas in the tank had gotten very old, so I've tried cleaning the carburetor, but it still doesn't work.
There is a needle valve on the outside that is covered with a plastic cap that I can't remove. I think this is the culprit.
Does anyone know how to remove the plastic cover for this needle valve. The cover has a notch on it that limits it's movement.
Anyone who can help me with this is worth a gazillion bucks.
Thanks.... Greg
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that screw only really affects the idle mixture. what is it doing? the problem may be elsewhere if we knew what the real symptoms were we could help Chip
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a
cap
The
Ahhhhhh.... I knew I was forgetting something.
I can get it to start and run (sort of) if I squirt gas down the barrel of the carb. If don't do that, it won't start at all. As soon as I quit squirting gas, it quits.
The fuel pump seems to work because I tried to start it with the top of the carb off. When I did that, gas was squirting up from the input of the carb. The bowl was full of gas. The float and float valve seem to move freely.
Originally, when the problem first started, the engine would start, but ran roughly and didn't have enough power to continue running if I put any kind of load on the generator (i.e.. tried to run my compressor off the generator).
Thanks for your response,
Greg
PS. I finally got the cap off that "idle mixture" screw and you are right - it wasn't the problem.
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you have to have a restriction in the main jet. if it runs on prime and the pump works, that's where you need to look. take the carb apart and run a wire through the passages, one of them is stopped up. Chip
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