I assume you are talking about an electric
fuel pump like I have on my YSE8. Is the
pump running when the ignition is on? Are any
fuel valves between the tank and
pump closed? Is the vent on the
fuel tank restricted in any way? How are the filters? There is usually 2, a Racor or similar and the smaller one on the engine itself. Is the
fuel in the tank clean? Follow the route from tank to injector and check everything, make sure the connections are tight and that air isn't getting in anywhere.