How can I do this test:


that check valve was faulty. So when you would test the pressure on the shrader valve with a gauge it would pressurize fine, but when the jump was done priming it would drop to 0 instantly.

I can test the pressure at the shrader valve but I don't know how to test it once it is done priming. Do I turn it on, let the pressure build up and shut the car off and see if the pressure leaks down?

 

Exactly! You hook that gauge to the schrader valve, turn the key on and look for pressure. Start it up and watch the pressure. Shut it down and watch for a pressure drop. It should hold pressure after shut down without loss. If you're pump is messed up it will drain off the pressure back into the fuel tank and that explains your long start-ups when "cold".