I have a 2002 Mercury 25hp remote start motor. Engine will not start unless I pull out the manual primer knob located on the outboard. Then the engine will start and will run until I push the primer knob back in. The engine will run for 15-20 seconds then dies. I have cleaned out fuel system, repalced fuel, replaced spark plugs, sprayed carb with carb cleaner. Does anyone have any ideas for me on what the problem may be? I'm baffled!