From:
McDDD

"Quote"

Checking the remote needle valve for air leaks.

The easiest way is to start by filling the tank.
Make sure the inlet and outlet fuel lines are connected to the remote needle valve.
Open the needle valve about 3 turns.
Disconnect the fuel line from the carb nipple.
Plug your fuel pump line fitting into this fuel line.
Turn on or crank the fuel pump in reverse to suck the fuel out of the tank and back into the fuel can.
Look closely at the fuel lines.

If you see bubbles in the fuel line going into the remote needle valve, then the line from the tank to the remote needle valve is leaking air into the fuel system. Find and fix the air leak, then move on to checking the remote needle valve.

If you see clear fuel in the fuel line going from the tank into the remote needle valve, and see bubbles in the line that goes from the remote needle valve to the carb nipple, then air is leaking into the remote needle valve assembly from somewhere. Find the air leak and fix the problem before doing anything else.

If you see clear fuel in the fuel line going from the tank into the remote needle valve, and clear fuel in the line that goes from the remote needle valve to the carb nipple, then there are no air leaks.....and the remote needle valve isn't the problem.

"End Quote"