I have an onan generator on my 1977 Dodge. The fuel pumps seems to be working however it starts hard. If I spray some starter fluid in the air filter, it starts right up, no problem, then will continue to run just fine. If I shut it off, wait a few minutes, even a few hours, then it will start right up again, but if I wait overnight, she won't start up again, till I get out the starter fluid spray. I put in brand new plugs, but no difference. Any help is greatly appreciated, thank you!