Also,

If you are running a check valve on the vent line, make sure that it is not sticking. Usually on my first start of the day, I'll turn the ignition off and spin the motor at full throttle for 3-5 seconds to let is get the engine good and wet, and then turn the ignition on and it ill usually fire immediately. After the first start of the day, this is usually never a problem. You might also try richening the pump a little on the bottom. The engine seems to run fine with the bottom a little lean, but it is harder to start.

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