papaglide 541 #1 Posted May 10, 2010 when my onan is running, not only is it surging, the vacuum gauge is fluctuating between 10 and 16. The surging and vacuum fluctuating happens from idle all the way to wide open. Is this a clue as to why it is surging? Share this post Link to post Share on other sites
rickv1957 70 #2 Posted May 10, 2010 More than likely needs a good carb cleaning,Rick Share this post Link to post Share on other sites
rick 217 #3 Posted May 11, 2010 Have you checked the compression? What is the difference between the cylinders? Share this post Link to post Share on other sites
Raider12 13 #4 Posted May 11, 2010 Any time you have surging issues your vacum will fluctuate up and down. This is a common problem with the carbs on the Onan engine. Generaly the carb needs a good cleaning. Share this post Link to post Share on other sites
markslawnmowerworld 4 #5 Posted May 11, 2010 Try running a bottle of seafoam through the gas tank...see if it clears up! :D Share this post Link to post Share on other sites
papaglide 541 #6 Posted May 11, 2010 Have you checked the compression? What is the difference between the cylinders? I don't know how to check the compression. wish I did though... Share this post Link to post Share on other sites
papaglide 541 #7 Posted May 11, 2010 More than likely needs a good carb cleaning,Rick I took the air cleaner off and used air to blow out the choke plate and throttle plate. I then sprayed carb cleaner on the choke plate and throttle plate while the engine was running. No change. Share this post Link to post Share on other sites
Horse Fanatic 49 #8 Posted May 11, 2010 Carb cleaning meaning the bowl and passages, not the bore. You have to at least take the top off the carb. Share this post Link to post Share on other sites
Fiddlestix 0 #9 Posted May 11, 2010 ooppps! Double Post! :D Share this post Link to post Share on other sites
Fiddlestix 0 #10 Posted May 11, 2010 You sure this isn't just the governor hunting? Perhaps, just unhook the governor from carburetor and manually hold throttle plate/arm in a position and see. That would determine if a fuel delivery/ignition issue or if it is the governor hunting. Share this post Link to post Share on other sites
papaglide 541 #11 Posted May 11, 2010 I saw the governor hunting scenario in the onan manual but didn't know if that was a common occurrence or not. I will try that this morning. Share this post Link to post Share on other sites
papaglide 541 #12 Posted May 11, 2010 Well, I took the governor from carburetor and the engine didn't surge. So maybe it may be hunting and needs to be adjusted. Share this post Link to post Share on other sites
papaglide 541 #13 Posted May 12, 2010 I put on a new fuel filter and adjusted the governor to the hole closest to the carb and voila!! It doesn't purr like a kitten 'cause the muffler's to dam loud BUT she's runnin' pretty dog gone good. Thanks for the help. Share this post Link to post Share on other sites
