I have a old 16HP 1 cylinder Kohler in a Wheel Horse garden tractor. I use this old tractor for snow removal and odd jobs. It takes spells when it will not run above an idle. I have removed the carb and cleaned it out, it seems to run OK for awhile then starts cutting out and will die unless I return the throttle to idle. I have taken the fuel line off the carb and cranked it over to see if the fuel pump works. It does pump some gas but not like a car fuel pump when you perform this test. How much pressure or volume should the pump put out? I am sure the engine is starving for fuel, either the main jet is getting plugged or the fuel pump output is low. Any other ideas?