I'm having a hard time bleeding the fuel pump. I'm getting and bleeding fuel into the filters ok but not into the fuel pump thus none through the injector lines. We're getting a slight drip of fuel from the bottom of the pump and am wondering if that is creating an air gap. The tractor was running fine before we had the steering motor valve rebuilt and replaced but now it won't start. Any suggestions how to bleed fuel system properly. It's gravity fed.