1996 Johnson 115 on 18' Bonita with fuel tank mounted in bow. Recently replaced all fuel lines and water separator. Engine runs and starts great. After turning off motor for very short time, it restarts with no problem. However, if it sits for a few minutes, like when fishing a spot for a few minutes, when I start the motor to move to another hole, it runs like it is missing until I get up to 4000 rpm. Runs great to next hole, where I again kill the engine. If I crank it right up, it runs fine. If we sit there a few minutes, same problem. I am suspecting a bad fuel pump, but am also curious about the check valve which was removed by my mechanic a few weeks ago. Will the lack of the check valve allow all fuel in the lines to drain back to the tank ( I ask because I noticed after sitting for a few minutes the primer bulb is empty)? My theory is that the check valve is allowing the fuel lines to empty and relieve any required pressure, and that the fuel pump is weak (going bad) and has difficulty drawing sufficient fuel for take off, until the pressure of high rpm's pulls adaquate fuel into the lines. Any opinions?