fourwheels0 191 #1 Posted July 10, 2014 does anyone have a video of carb cleaning on a onan 20 hp. i've looked on you tube and couldn't find anything. thanks. Share this post Link to post Share on other sites
WH nut 553 #2 Posted July 10, 2014 Depends on how far you want to go. If you just want to get the crude out of the bowl, just remove the top. Pretty straight forward. If you want to remove the whole carb then you need to remove the intake, which is also pretty straight forward. Its a simple carb so there aren't many pieces. Share this post Link to post Share on other sites
HokieAg07 129 #3 Posted July 11, 2014 Its not bad Mike, most of the time for a quick cleaning I just take the top of the carb off and clean the bowl, and blow out what I can. Taking the entire carb off for serious cleaning requires intake manifold removal as the bolts are on the underside. You can modify a wrench to get to the bolts as well. I replaced the emissions carb on my 96 520 with a new non emissions carb last year, best thing I ever did! 1 1 Share this post Link to post Share on other sites
fourwheels0 191 #4 Posted July 11, 2014 ok sounds like it may not be as bad as i thought (never done an onan carb before). it spits and sputters with the choke on then quit's after a few minutes. i'll find out sunday when i pick up the tractor. thanks guys. Share this post Link to post Share on other sites
Tankman 3,518 #5 Posted July 13, 2014 My '90 520-8 had carb problems too. Was sittin' for a couple of years when I found it. Used Gumout carb cleaner. Improved. Then, by suggestion, tried Berryman's fuel additive. Bit by bit, engine sounded better. Runnin' like a Horse now! I believe! 1 oz. per gallon of gas, Berryman's! http://www.berrymanproducts.com/products/gasoline/b-12-chemtool-carburetor-fuel-system-and-injector-cleaner/ http://www.berrymanproducts.com/products/cleaning-degreasing/b-12-chemtool-carburetor-choke-and-throttle-body-cleaner/ Share this post Link to post Share on other sites
Tankman 3,518 #6 Posted July 13, 2014 My '90 520-8 had carb problems too. Was sittin' for a couple of years when I found it. Used Gumout carb cleaner. Improved. Then, by suggestion, tried Berryman's fuel additive. Bit by bit, engine sounded better. Runnin' like a Horse now! I believe! 1 oz. per gallon of gas, Berryman's! http://www.berrymanproducts.com/products/gasoline/b-12-chemtool-carburetor-fuel-system-and-injector-cleaner/ http://www.berrymanproducts.com/products/cleaning-degreasing/b-12-chemtool-carburetor-choke-and-throttle-body-cleaner/ Share this post Link to post Share on other sites
fourwheels0 191 #7 Posted July 13, 2014 tankman thanks. mine won't run for more than a minute and will not rev up all the way and surges. i'll take the carb off and fully clean it and the entire fuel system. i do see partical's in the filter. should the fuel filter stay full of fuel when you shut it off or when the engine dies?. mine seems to go back to empty very shortly after. Share this post Link to post Share on other sites
Martin 2,131 #8 Posted July 13, 2014 i have done the Onan carbs both on and off the engines. On the engine gets most of the problems solved most of the time. Even if you are only having problems at high rpm, the idle circuits feed the carb throughout the rpm, so its best to look at every area of the carb. most of the junk that i have removed with tip cleaners, carb cleaner, sea foam or other cleaners wouldn't remove. so you need to check all the small holes and inside the brass tubes that they are clear. there is a tube or tubes (depending on whether its an emissions carb) that is pressed into the top of the carb, you will see it when you pull the top off, the little holes along the sides of the tube get blocked, the end is supposed to be blocked off on one of them (the older non emissions carbs with one tube is supposed to be blocked on the end) so don't worry about that. this is the top of an emissions carb..... also the idle tube that screws in to the main body of the carb needs to be removed and cleaned. this tube has holes along the sides and at the end, you should be able to see right through it from end to end and sideways through the holes...... heres a pic of the idle tube that needs to be unscrewed from the main body, this one is just sitting in the hole with the threads exposed.... make sure the fuel bowl is completely clean, anything there is going to be sucked up by the main jet. you will see that at the bottom of the bowl to the front of the carb as it sits on the engine. this can be removed by removing the plug in the side of the carb and then using a tight fitting flat blade the jet can be unscrewed. i have found junk behind the main jet in those passages too. they can be flushed by squirting carb cleaner down those holes in the top (see approx 3/16 size holes next to idle tube in above pic) and through the holes where the idle and main are. main jet plug location, main jet is back in behind this hole on the inside of the fuel bowl.... watch your eyes and skin, the carb cleaner can shoot back at you on occasions.... heres my first dealings with a p216 with the nikki carb, a 95 pre emissions one, there is a better pic of the idle tube removed and the holes to clean..... 1 Share this post Link to post Share on other sites
fourwheels0 191 #9 Posted July 14, 2014 thank you martin that's just what i was looking for and hoping i can get mine running good. Share this post Link to post Share on other sites
fourwheels0 191 #10 Posted July 14, 2014 ok update. i got the carb cleaned (used gunk carb cleaner in the 1 gallon can with the parts bucket inside). BUT i lost the little rod that operates the choke. does anybody have one they can send me?. it goes from the choke cable bracket up to the top of the carb to move the butterfly. Share this post Link to post Share on other sites
HokieAg07 129 #11 Posted July 15, 2014 ok update. i got the carb cleaned (used gunk carb cleaner in the 1 gallon can with the parts bucket inside). BUT i lost the little rod that operates the choke. does anybody have one they can send me?. it goes from the choke cable bracket up to the top of the carb to move the butterfly. Mike, I should have one on my old carb I took off. I can check tomorrow morning and let you know. 1 Share this post Link to post Share on other sites
Martin 2,131 #12 Posted July 15, 2014 if you get stuck, i could measure one. fabricating one from some wire shouldn't be too hard....... Share this post Link to post Share on other sites
fourwheels0 191 #13 Posted July 15, 2014 Mike, I should have one on my old carb I took off. I can check tomorrow morning and let you know. chris thank you. let me know. martin do you know what the setting is on this brass screw?. i think it was 1 turn out but not sure. Share this post Link to post Share on other sites
fourwheels0 191 #14 Posted July 15, 2014 ok it's back to surging and won't idle. it ran good before i put it all back together or i thought it did (gas tank,seat pan,seat ect.) the gas gauge doesn't work and i'm thinking it may be electrical. i'm gonna unplug the gas gauge and see if that changes anything. i've got fresh fuel with fresh seafoam in it. Share this post Link to post Share on other sites
Martin 2,131 #15 Posted July 15, 2014 (edited) 1 1/4 turns out, are you sure you got all the little holes clear? These are not your grandmas old kohler carb you know........ they will take you on a journey to higher levels of carb cleaning...... Sent from my iPhone using Tapatalk Edited July 15, 2014 by Martin 2 Share this post Link to post Share on other sites
Martin 2,131 #16 Posted July 15, 2014 (edited) I see your problem from your pic......... Above the mixture screw there is supposed to be a small plug covering that hole, (look inside you will see 2 or 3 little holes through to the venturi) yours is missing, probably blew out while cleaning....... This will most definitely cause the symptoms you have now...... Sent from my iPhone using Tapatalk Edited July 15, 2014 by Martin 2 Share this post Link to post Share on other sites
fourwheels0 191 #17 Posted July 15, 2014 martin i was wondering about that and yes i do see little holes in there. what should i use to plug it back up?. Share this post Link to post Share on other sites
fourwheels0 191 #18 Posted July 15, 2014 MARTIN you are the man!!!!!!!!!!!. sure enough i went and put my finger over it and it fired right up and idled perfect and revs up wide open with NO surging. i can't thank you enough!!!!!!!!!!!!!!. 1 Share this post Link to post Share on other sites
Martin 2,131 #19 Posted July 15, 2014 I would look for the plug in your carb cleaner. I think they are available through jd dealers as an individual part, but onan makes you buy a kit to get them. Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
fourwheels0 191 #20 Posted July 15, 2014 ya it's not in the cleaner. i think your right that it blew out when i hit it with the air hose to blow everything out. for now i have a piece of heavy duty duct tape over it. well live and learn at least now i know what to do and what NOT to do on these carbs lol. thanks again martin. Share this post Link to post Share on other sites
Martin 2,131 #21 Posted July 15, 2014 It was Jack (Wishin4a416) who told me the JD dealers carried the part. i think its relatively inexpensive, would be worth the effort to replace it as the duct tape probably won't last too long with the heat etc in that area...... 1 Share this post Link to post Share on other sites
fourwheels0 191 #22 Posted July 15, 2014 ya the tape is just a temporary fix. i'll check with the local jd dealer thanks. just got done mowing the pasture with it and it ran and cut great. 1 Share this post Link to post Share on other sites
fourwheels0 191 #23 Posted July 17, 2014 ok i got a plug from a friend of mine (oldredrider) and all is good now. i still need the choke linkage. it's part #153-0500 if anyone has one they want to part with. Share this post Link to post Share on other sites
HokieAg07 129 #24 Posted July 19, 2014 Mike I forgot to tell you but I guess the new carb did not come with linkage as I dont have any linkage laying around. Share this post Link to post Share on other sites
jgc1159@gmail.com 0 #25 Posted April 26, 2017 I have a WH520H that won't idle without being slightly chocked and surges at full throttle do you think I could fix the problem by just removing the top of the carb Share this post Link to post Share on other sites
