i have a 5000 watt onan generator with about 700 hours and i've had to bring it to a rv dealer to have it checked at. the problem im having with it is keeping it running. first time the gas was getting into the crank case and running on 1 cylinder. well no more than 2 weeks later i go to crank it and it won't even run now. will run for 3 secs and die. i smelled the oil again and it seems that it has the same problem again. they said they replaced the following parts check valve oil of course oil filter air filter 2 sparkplugs anyone ever heard of such a problem and if so what else could it be?