Onan carb fix
I have a 5500 onan in my new fuzion and it's always had a lean pop out the exhaust and would surge when not under a load. I am a diesel tech and refused to buy into the fact these carbs can't be cleaned and made to run good again.
I always ran seafoam and ran the generator under load once a month. I finally gave up on the seafoam and removed the carb for cleaning. Once I got the carb off I took it to work and took the carb completely apart. No signs of dirt or varnish and jets where clean. We have a ultrasonic carb cleaning so I dropped the carb into it and let it do it's thing. Once done I washed out the carb and blew it out with air. Next I took some gasket paper and made 2 new gaskets to replace one on top of carb and one that goes between carb and intake. Took the carb back home and installed it back on the generator along with 2 new spark plugs. The gen fired right up but the lean pop was still there and surge was a little better. I knew this carb was clean because it ran good but just had this small lean pop.
Well I wasnt going to give up so I called the small engine mechanic at work and told him what was going on. He told me to bring him the carb because he knows what's wrong with it. I removed the carb again and took to work the next day. I gave him the carb and he said give me a few minutes to fix it. 20 minutes goes by and he walks up to me and says your done. I ask him what was the problem. He brings to tell me he sees it all the time with these new generators and small engines. He says they are running these engines so lean because of emissions standards today. He shows me a set of real tiny drills to drill out main jets. He found the stock main jet size to be .0250 and just opened it up to the next jet size of .0280. One size wasn't a big jump but he says trust me that's all it needs.
So I take the carb home and installed it back onto the generator. Prime the carb and say to myself well here goes nothing. The motor fired right up and.....WOW! This generator has never ran this good from day one. This thing sounds totally different. I start to think this thing sounds quieter also. Next thing I know my wife walks up and says man it sounds quieter. lol I also installed a shut off valve in the fuel like so I can run the generator out of fuel.
I always ran seafoam and ran the generator under load once a month. I finally gave up on the seafoam and removed the carb for cleaning. Once I got the carb off I took it to work and took the carb completely apart. No signs of dirt or varnish and jets where clean. We have a ultrasonic carb cleaning so I dropped the carb into it and let it do it's thing. Once done I washed out the carb and blew it out with air. Next I took some gasket paper and made 2 new gaskets to replace one on top of carb and one that goes between carb and intake. Took the carb back home and installed it back on the generator along with 2 new spark plugs. The gen fired right up but the lean pop was still there and surge was a little better. I knew this carb was clean because it ran good but just had this small lean pop.
Well I wasnt going to give up so I called the small engine mechanic at work and told him what was going on. He told me to bring him the carb because he knows what's wrong with it. I removed the carb again and took to work the next day. I gave him the carb and he said give me a few minutes to fix it. 20 minutes goes by and he walks up to me and says your done. I ask him what was the problem. He brings to tell me he sees it all the time with these new generators and small engines. He says they are running these engines so lean because of emissions standards today. He shows me a set of real tiny drills to drill out main jets. He found the stock main jet size to be .0250 and just opened it up to the next jet size of .0280. One size wasn't a big jump but he says trust me that's all it needs.
So I take the carb home and installed it back onto the generator. Prime the carb and say to myself well here goes nothing. The motor fired right up and.....WOW! This generator has never ran this good from day one. This thing sounds totally different. I start to think this thing sounds quieter also. Next thing I know my wife walks up and says man it sounds quieter. lol I also installed a shut off valve in the fuel like so I can run the generator out of fuel.
