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.
Living aboard in Victoria Harbour