Tgalo 121 #1 Posted August 12, 2020 What else besides the obvious can cause a P220 surge. I cleaned the carb out and resealed the intake. Ran great for a while now the surge is back. About 600 hrs on it. Thanks, T Share this post Link to post Share on other sites
oliver2-44 10,715 #2 Posted August 12, 2020 Your carb may have gotten recontaminated by junk in the rest of the fuel system or from fuel tubing deteriorating due to the effect of ethanol in the gas. Do you have a fuel filter near the carb, You may need to clean the rest of the fuel system and replace the fuel hoses. Share this post Link to post Share on other sites
Tgalo 121 #3 Posted August 13, 2020 Yeah theirs a filter in the normal spot just before the carb. But when I went though the restoration I replaced all the lines, new petcock and cleaned out the tank completely. Im thinking of buying a new carburetor maybe. Share this post Link to post Share on other sites
Skwerl58 763 #4 Posted August 13, 2020 Since you took care of the surge and it returned I would go back into the carb, clean it and use only non ethanol fuel. Share this post Link to post Share on other sites
lynnmor 7,817 #5 Posted August 13, 2020 Rarely does a carb need replaced, usually cleaning and adjusting is all that is needed. If you could describe the surge, maybe we could be of more help. For example, a recent post saying surge turned out to be periodic over-speed. Share this post Link to post Share on other sites
Ed Kennell 41,961 #6 Posted August 13, 2020 It took three cleanings of the carb to stop the surging on my P220 ONAN. Share this post Link to post Share on other sites
Tgalo 121 #7 Posted August 13, 2020 (edited) 8 hours ago, lynnmor said: Rarely does a carb need replaced, usually cleaning and adjusting is all that is needed. If you could describe the surge, maybe we could be of more help. For example, a recent post saying surge turned out to be periodic over-speed. Ok well for instance yesterday when I took it out to mow the lawn it started and ran fine. Now its pretty hot here in VA but when I idled it down to empty the bags, about 20 minutes of full throttle, there the surging was back. So it seems the worst at idle and better at higher RPM. I use only non ethanol mogas in it 93 octain. Im wondering if the filter could be letting some crap though. I guess I could clean it out again... Thanks, T Edited August 13, 2020 by Tgalo Share this post Link to post Share on other sites
lynnmor 7,817 #8 Posted August 13, 2020 It sounds like a vacuum leak. Did you pull the manifold and check it for leaks when you cleaned the carb? There is a welch plug just above he idle mixture screw that should be removed to clean in there, you will need a new 3/8” aluminium to replace it. I think we get carried away about gasoline, I hate ethanol as much as anyone but your engine will run on regular grade with up to 10 percent ethanol. 1 Share this post Link to post Share on other sites
Tgalo 121 #9 Posted August 13, 2020 1 hour ago, lynnmor said: It sounds like a vacuum leak. Did you pull the manifold and check it for leaks when you cleaned the carb? There is a welch plug just above he idle mixture screw that should be removed to clean in there, you will need a new 3/8” aluminium to replace it. I think we get carried away about gasoline, I hate ethanol as much as anyone but your engine will run on regular grade with up to 10 percent ethanol. I did reseal the manifold half's with ultra grey, then made a jig to vacuum test it. It held perfectly. But the welch plug may be an issue. I will look at that... Share this post Link to post Share on other sites
clueless 3,235 #10 Posted August 13, 2020 2 hours ago, lynnmor said: It sounds like a vacuum leak. Did you pull the manifold and check it for leaks when you cleaned the carb? There is a welch plug just above he idle mixture screw that should be removed to clean in there, you will need a new 3/8” aluminium to replace it. I think we get carried away about gasoline, I hate ethanol as much as anyone but your engine will run on regular grade with up to 10 percent ethanol. I believe that's a Nikki carb. I have one on a Kohler TH18 that started to surge (hunting) a few years ago after replacing everything from the tank to the carb, and cleaning the carb twice it would starting hunting, starving for gas, after a few minutes. Took it to the local dealer they cleaned it in some sort of a sonic bath and rebuilt it after I put it back on and drove it about 10 minutes same old thing . I parked it and decided to find a replacement carb, ended up on the Simplicity site, a member who knew all about these TH18s told me to pop the welch plug out and clean out the orifice behind it with some carb cleaner, a very small tip cleaner and blow it out with some a air house. It's been running fine ever since . Also replace the welch plug with a new one. Share this post Link to post Share on other sites
Tgalo 121 #11 Posted August 13, 2020 Sounds like what I got going on. Im not at home right now, can you get to that plug without pulling it off? Wishful thinking Share this post Link to post Share on other sites
lynnmor 7,817 #12 Posted August 13, 2020 2 hours ago, Tgalo said: Sounds like what I got going on. Im not at home right now, can you get to that plug without pulling it off? Wishful thinking Maybe, but it would be better to remove the carb. NAPA may have a selection of Welch plugs, it is easy to damage the aluminium ones so you might want a couple. There are two ways to get the old one out, drill a hole in the middle and pry it out, or try punching the Center to cause it to pull the sides in. Be careful to not drill or punch very deep. I use a very small amount of sealant on the edges when installing. Using a paint brush bristle is a good way to probe the holes inside. Share this post Link to post Share on other sites
