JaysHorse 287 #1 Posted March 10, 2014 My onan runs great but when I turn throttle all the way down it runs well for about 3-5 mins then starts sputtering and dies. I still notice fuel in the filter. Also fires right back up no prob. Ideas? Share this post Link to post Share on other sites
Hodge71 663 #2 Posted March 10, 2014 Never rebuilt an Onan carb but there may be a low speed idle screw or jet thats dirty and needs to be cleaned or whole carb rebuilt. I had a Kohler do the same thing and it was fine after I disassembled and rebuilt the carb. Theres lots of little holes in them that can get crudded up from junk gas Share this post Link to post Share on other sites
JaysHorse 287 #3 Posted March 10, 2014 That may be the case. The guy I just purchased it from said it's been sitting for about 3 or 4 yrs. thanks for the idea. Share this post Link to post Share on other sites
Desko 552 #4 Posted March 10, 2014 Welcome to Red Square. I believe the 216-218 are emissions style carb no adjusting screws Share this post Link to post Share on other sites
Martin 2,130 #5 Posted March 10, 2014 (edited) the emissions carbs didn't come about until spec g. spec a-f had a idle screw. if the carb (nikki) has an accelerator pump on the side it is a spec g carb and therefore a plug is there instead of adjusting screw. the accelerator pump is a dome shaped area on the side. heres two carbs, the one on the left is a spec g carb (accel pump) the one on the right is a-f ( no pump). you can see the lower idle hole has a plug on the left instead of a screw as on the right carb. im not sure when spec g started, i do know that my 1995 416H has a spec d engine and my 1995 416-8 has a spec g engine (california emissions). Edited March 10, 2014 by Martin Share this post Link to post Share on other sites
JaysHorse 287 #6 Posted March 10, 2014 (edited) According to my manual it is a G. I think that's what the G is in P218G correct? What options or fixes might I do with? Edited March 10, 2014 by JaysHorse Share this post Link to post Share on other sites
Desko 552 #7 Posted March 11, 2014 I seen a video on YouTube where a guy punched the cap off and adjusted it as there is a screw underneath it it is just capped off Share this post Link to post Share on other sites
Martin 2,130 #8 Posted March 11, 2014 According to my manual it is a G. I think that's what the G is in P218G correct? What options or fixes might I do with? nope, the G as in P218G is not the spec but the model number. look at your tag on the engine...... its the last letter of the model and spec number.... model # P216G-I spec # 10976D D is the spec on this tag....... so it had a pre emissions carb from the factory. look at your tag and if it has the factory carb (or same replacement) you will know what you have. Share this post Link to post Share on other sites
JaysHorse 287 #9 Posted March 11, 2014 Says P218G-I / 10539B. Does that mean its a B? Share this post Link to post Share on other sites
JaysHorse 287 #10 Posted March 11, 2014 Really odd! The model # on the tractor is 31-18OE01 and the engine is P218G-I / 10539B. According to the tractor number it's an '88 but according to the engine model it's an '89. What gives? Do I have a hybrid/mutt? Lol Share this post Link to post Share on other sites
Martin 2,130 #11 Posted March 11, 2014 (edited) P218G-I / 10539B was used on 1988 and 1989 518H. (31-18OE-01 and 31-18OE-02) and yes it is a B so you should have a non emission carb if original. Edited March 11, 2014 by Martin Share this post Link to post Share on other sites
JaysHorse 287 #12 Posted March 11, 2014 Yes I just went out and looked at it and I do have the adjustment screw. Could this be the reason why I also smell like I've been sitting in a locked room with it running when I'm done riding? I'm just not used to onans. They are Greek to me. Share this post Link to post Share on other sites
Martin 2,130 #13 Posted March 11, 2014 smell like gas? maybe its too rich. adjust it first per the manual. ( turn in until lightly seated and then out 1 1/4 turns) see how it runs like that. in and out just a little and see if that smooths it out. you could have an out of adjustment carb or some crap in the idle circuit. these carbs are very sensitive to dirt and junk in the fuel. normally that would make them repetitively surge high and low in the revs. if you are still having issues after adjusting the idle properly i would recommend that you take the top off the carb and clean out the bowl and also pull the idle needle and clean. every Onan carb I've had that has idle problems, the idle needle has been blocked in one of the small holes..... Share this post Link to post Share on other sites
dbartlett1958 96 #14 Posted March 11, 2014 Yes I just went out and looked at it and I do have the adjustment screw. Could this be the reason why I also smell like I've been sitting in a locked room with it running when I'm done riding? I'm just not used to onans. They are Greek to me. Listen to Martin! He has more Onan's than any sane person should. 1 Share this post Link to post Share on other sites
Martin 2,130 #15 Posted March 11, 2014 (edited) this issue sounds more like an out of adjustment thing right now. is it running smooth in the 3-5 minutes before running rough and dying? if its not as smooth as it should be ( these engines run nice when well tuned) i would look at the carb internals. try the simple things first, adjusting the idle screw..... Edited March 11, 2014 by Martin Share this post Link to post Share on other sites
JaysHorse 287 #16 Posted March 13, 2014 Yes I smell like gas. The idle is smooth for the first 3-5 then surges and eventually stalls out. I haven't had the chance to play with the idle screw yet. Had to take my wife in for the birth of our daughter. But hoping to try the adjustment in the morning and blow some snow(14"). Share this post Link to post Share on other sites
JaysHorse 287 #17 Posted March 13, 2014 They sure don't make it easy to get to that screw! Take half the tractor apart to get to it! : ( Share this post Link to post Share on other sites
Hodge71 663 #18 Posted March 13, 2014 (edited) Another reason why I despise Onan engines....I can't wait to finish the restore on my 416 this spring and send it down the road for a nice C-165 or 175. Hope you get her worked out to get rid of that 14" of new snow Jay Edited March 13, 2014 by hodge71 Share this post Link to post Share on other sites
Martin 2,130 #19 Posted March 13, 2014 You should be able to reach it with just a long screwdriver. Maybe your muffler bracket doesn't have the hole in the middle? I have found both of mine easy to adjust while running. Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
JaysHorse 287 #20 Posted March 13, 2014 That's exactly it. No hole in the bracket. Nothing a drill bit can't fix. Share this post Link to post Share on other sites
