me and my buddy went to lake last nite and his motor started well and idled perfect but would die when going to full throttle. i thought it was the vent on the gas cap, it was open. we disconnected the fuel hose and squeezed the bubble and he was getting gas to motor. the choke was not stuck and his throttle and cables were all working properly. it would accelerate when he constantly pushed the choke while under way. i also noticed his primer bulb was soft after running a few minutes. what could be the problem? it's a 1983 or 84 35 johnson sea horse.