sdgmc05 0 #1 Posted August 7, 2012 Picked up this tractor a few weeks ago and was running perfect, just recently it won't start unless half choked (even when 90+degrees) and surges like crazy at any engine speed. Driving me crazy! Is this something as simple as a dirty carb? Or intake valves not adjusted right? I replaced all fuel line and filter and fuel pump is working as it should. Tractor has 362 hours on the clock. Any help would be great, thanks in advance! Share this post Link to post Share on other sites
TheReDStAnG 4 #2 Posted August 7, 2012 Sounds like a dirty carb. I would start by blasting the little holes in the throat of the carb with carb cleaner and compressed air. That usually takes care of it, but sometimes you have to pull them off for a full soak. Share this post Link to post Share on other sites
JackC 617 #3 Posted August 8, 2012 Your problem sound like the one I had with my 520HC. I agree, sounds like a carburetor cleaning is needed. I cleaned the carburetors on my 520HC and D-160 recently with great results. I can buy ethanol free fuel in NY state and I will now start using it exclusively in all my equipment with carburetors. Share this post Link to post Share on other sites
sdgmc05 0 #4 Posted August 8, 2012 I cleaned the carb thoroughly and it runs a lot better, but not perfect. There is a lot of rust in the fuel pump from the rivet holding the reeds in and there seems to be a leak in one of the gaskets.....I was thinking about bypassing the vacume fuel pump and using a low pressure electric unit.(don't want to spend $50+ on a onan) What do you think? Share this post Link to post Share on other sites
stevebo-(Moderator) 8,539 #5 Posted August 8, 2012 I think even tho you cleaned the carb it is still dirty. Clean it again. This is a frustrating point on the Onans. Not easy to properly clean these carbs. Share this post Link to post Share on other sites
JackC 617 #6 Posted August 8, 2012 Someone here said they purchased a new Briggs and Stratton vacuum fuel pump for about $20 that is similar in size and function to the ONAN pump. Share this post Link to post Share on other sites
zeedubbya 18 #7 Posted August 11, 2012 Clean that carb again and adjust the valves. See if you've got fuel spraying out of the top of the carb. Mine was running just like you said-- I cleaned the carb twice, then adjusted intake and exhaust valves. Intake on back cylinder was more or less frozen in place. Let us know how it turns out. Share this post Link to post Share on other sites
