'75 15hp pull start Johnson. Put carb kit in and replaced slow speed needle after thoroughly cleaning carb. Engine idles OK, but when the power is advanced the motor will run for about 15 seconds but will then die. Neighbor who has go-kart experience says that it sounds like the engine is being starved. So, is there a way to tell if the problem is a bad fuel pump or maybe the float not adjusted correctly in the carb? Since I just rebuilt the carb, would prefer to eliminate the fuel pump before I take the carb apart agan.