If you don't have an adjustable main jet then there is nothing there to screw in. There will be a cap over the hole. If it has a T handle it is an adjustable jet.
In my experience the adjustable jet should be fully open for normal driving and leaned (screwed in a bit) for higher altitudes.
I'd start about 1-1/2 turns on the air mixture.
However, neither of these have anything to do with the pump. It should squirt a shot of fuel even if the main and idle jets are closed. Did you clean the fuel screen in the carb?
