Alrashid2 429 #1 Posted 20 hours ago (edited) Hey guys. I've noticed this phenomena with my Horse before, but not nearly this bad. When it is cold out, despite warming the tractor up, my exhaust will constantly be popping during operation, almost sounding like a backfire. Usually it only happens once a minute or so, but today in this <20F weather, it was happening every few seconds. On top of this, the RPMs seemed to be really fluctuating, and I even had a few cases where it dropped for a few seconds then sped back up. It almost reminded me of when youd engage the PTO in wet grass, but I was just standing still when this would happen. I took a video, but now that I'm watching it it isn't doing it justice. Can't really hear the pops, but if you listen closely you can kind of hear the fluctuations in RPM. This never happens in the summer, only winter. Any ideas here? My only guess was that this was actually backfiring, and my carb might be running rich when in cold weather, but not in warm weather? Not sure if that makes sense though. I suppose I could try tweaking the carb adjustments but wasn't sure where to start. Thanks for the advice fellas! PXL_20251215_175154772_TS.mp4 Edited 20 hours ago by Alrashid2 Video Share this post Link to post Share on other sites
ebinmaine 75,727 #2 Posted 18 hours ago 2 hours ago, Alrashid2 said: running rich when in cold weather, but not in warm weather? The opposite actually. Cold air is denser so more can get in. Cold fuel doesn't atomize (spray) as well either. Sort of a double negative. More air and less effective fuel spray means you're likely running lean. Not the best for an engine.... Try turning the adjustment screw(s) Just a tad... out. Experiment and report back. 3 3 Share this post Link to post Share on other sites
Alrashid2 429 #3 Posted 18 hours ago 2 minutes ago, ebinmaine said: The opposite actually. Cold air is denser so more can get in. Cold fuel doesn't atomize (spray) as well either. Sort of a double negative. More air and less effective fuel spray means you're likely running lean. Not the best for an engine.... Try turning the adjustment screw(s) Just a tad... out. Experiment and report back. Thanks @ebinmaine! That makes sense to me. I bet my carb is set "perfectly" for warm weather but the cold is throwing it slightly off. As you said, double negative. I'm sure I can richen the main jet a bit and it'll still run well in summer too. I won't have time to tinker until Fri but will report back then! Thanks! 2 Share this post Link to post Share on other sites
Handy Don 15,165 #4 Posted 18 hours ago All of the above, and... I’d make very sure there is no water in the fuel lines. Condensation can occur in the tank, the pump, and in the carb bowl. If the tractor storage is below freezing that can cause ice. Me? I’d try for a warm enough place for the tractor for 24 hours, then dose the fuel tank with dry-gas per the instructions on the bottle. Then burn through ALL of that fuel before re-fueling. Share this post Link to post Share on other sites
Alrashid2 429 #5 Posted 18 hours ago @Handy Don how quickly does that happen? I burn through fuel pretty quick and just put fresh fuel in the tank 2 weeks ago. Store my wheel horse in the same place as my snow blower and lawn mower, and they've never had any issues with water or ice in the fuel system. Share this post Link to post Share on other sites
ebinmaine 75,727 #6 Posted 17 hours ago 6 minutes ago, Handy Don said: dry-gas @Alrashid2 do you use ALL ethanol free fuel? @Handy Don I've never seen ethanol laced fuel with water in it - but we have older machines with higher tanks, except one. Share this post Link to post Share on other sites
Handy Don 15,165 #7 Posted 17 hours ago (edited) 8 minutes ago, Alrashid2 said: @Handy Don how quickly does that happen? I burn through fuel pretty quick and just put fresh fuel in the tank 2 weeks ago. Store my wheel horse in the same place as my snow blower and lawn mower, and they've never had any issues with water or ice in the fuel system. Fueling and using that often, ice in the fuel system is probably not your issue. We have had members report carb icing in very cold but humid weather. It’d be visible as frost on the outside of the carb and the symptoms would be similar as it affects both air and fuel mixing in the carb throat. Edited 17 hours ago by Handy Don 2 Share this post Link to post Share on other sites
lynnmor 8,252 #8 Posted 17 hours ago 28 minutes ago, Handy Don said: Fueling and using that often, ice in the fuel system is probably not your issue. We have had members report carb icing in very cold but humid weather. It’d be visible as frost on the outside of the carb and the symptoms would be similar as it affects both air and fuel mixing in the carb throat. During a week long Christmastime power outage, I ran a generator the entire time except for fuel and oil stops. Carburetor icing was a real issue since a generator might run at the same throttle opening for some time and then when more power is called for the throttle plate is froze fast. My solution was to build a cardboard house to keep the heat in. I believe that ethanol laced fuel did stop nearly all of the ice in the fuel lines problems, but my example with the generator was not within the fuel touched parts. 3 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,842 #9 Posted 13 hours ago 1985 312-8 would have a K301 with points and condenser. Have another condenser you could try? Have you checked the valve clearances? They do not need it often but if never done a 1985 model is due. Have had success adding a shot of Marvel Mystery oil to the fuel or 2-stroke oil if you have it. Lubricates the valve stems in case they are lazy at closing. Do one thing at a time so you know what the fix is. 3 Share this post Link to post Share on other sites
