Gary Ginsberg 0 #1 Posted May 20, 2019 Wheel horse 312H. Model Kohler M12S... Specification 47 1527...Serial 200-8717493. Does this motor use points and condenser or is it electronic ignition? Starts nicley and runs great. After 10 minutes it runs very rough and I must pull out the choke to keep it running or it will stall. 10 minutes later it starts with no problem. New filter and foam prefilter have been installed., as well as new spark plug. Dropped the bottom of the carburetor and cleaned out the debris. New gas with stabilizer. Any thoughts what my next move is? Thank you, Gary Ginsberg Share this post Link to post Share on other sites
JAinVA 4,619 #2 Posted May 20, 2019 (edited) M series has electronic ignition.At the rear of the tractor under the fender pan is a fuel shut off.Turn the knob clockwise to shut off fuel.Disconnect fuel line from carb and put the end in a catch basin or can.Have some one turn on the fuel and see if you are getting good flow from the tank.If not you may have a clogged screen in the shut off valve.If it is clogged and you can't clean it, you will have to replace the shutoff valve.If you get good flow from the tank it sounds like a carb issue. Edited May 20, 2019 by JAinVA Share this post Link to post Share on other sites
wallfish 15,934 #3 Posted May 20, 2019 The Magnum engines do NOT have points and condenser. Another thing to check is if the gas cap vent hole is plugged. If it is, that will create vacuum pressure inside the tank as it uses fuel so try running it with the cap loose and see if the problem still exists. Many times just removing the bowl and cleaning that is not a good enough carb clean. Ethanol gas sucks and you may need to give it a more thorough cleaning but the running good for 10 minutes sure indicates the carb should be OK 1 Share this post Link to post Share on other sites
Gary Ginsberg 0 #4 Posted May 20, 2019 Sometimes it runs great for over 30 minutes without a problem, other times only 10 minutes. Gary Ginsberg Share this post Link to post Share on other sites
953 nut 51,754 #5 Posted May 20, 2019 The symptoms you described make me think vent in the gas cap is the most likely thing. As the fuel level goes down the tank takes a bit longer to develop a vacuum that the fuel pump can't overcome. To find ethanol free gas use this site. https://www.pure-gas.org/ Share this post Link to post Share on other sites
Gary Ginsberg 0 #6 Posted May 20, 2019 Thank you for your comments. Gary Ginsberg Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,503 #7 Posted May 20, 2019 1 hour ago, JAinVA said: M series has electronic ignition.At the rear of the tractor under the fender pan is a fuel shut off.Turn the knob clockwise to shut off fuel.Disconnect fuel line from carb and put the end in a catch basin or can.Have some one turn on the fuel and see if you are getting good flow from the tank.If not you may have a clogged screen in the shut off valve.If it is clogged and you can't clean it, you will have to replace the shutoff valve.If you get good flow from the tank it sounds like a carb issue. This is a good test but let the fuel tank completely drain and as it does watch for a consistent flow. What can happen is junk in the tank is almost weightless and when fuel flow stops the junk will drift away from the fuel valve. When flow starts again it is drawn back to the valve and filter by the fuel leaving the tank once again plugging the filter. Time for a soap and hot water flush on a sunny day to dry the tank. Garry 2 Share this post Link to post Share on other sites
oliver2-44 8,852 #8 Posted May 21, 2019 Good advice above. Share this post Link to post Share on other sites
ClassicTractorProfessor 5,262 #10 Posted May 21, 2019 Had a similar problem with my C125 a couple summers ago, took the line coming from the tank off at the pump, little to no gas flow. Blow into it until I heard the gas gurgling in the tank, reattach the line and it would run for a few minutes. Ended up taking the tank off, emptying it, and running a torch tip cleaner up into the shutoff valve and pulled out this nasty booger. Previous owner worked at the grocery store here, and bought all his gas there, which is a 10% ethanol blend. Gave the fuel system a good cleaning and she's been running like a top ever since. 2 Share this post Link to post Share on other sites
Gary Ginsberg 0 #12 Posted June 2, 2019 (edited) My 312h. After complete tuneup, carburetor rebuild, new filters and fuel lines it runs for 1/2 hour and still dies. Any clues? Gary Ginsberg 203-733-8431 glginsberg@gmail.com Edited June 2, 2019 by Gary Ginsberg Share this post Link to post Share on other sites
Gary Ginsberg 0 #13 Posted June 2, 2019 1/2 hour and it died Share this post Link to post Share on other sites
wallfish 15,934 #14 Posted June 2, 2019 Does it still have spark when it stops running? The idea is to isolate the issue between spark related or fuel related. 2 Share this post Link to post Share on other sites
Gary Ginsberg 0 #15 Posted June 2, 2019 Thanks I will check. It must have spark since after cooling off for 15 minutes it will restart run but soon after runs rough. Thanks for the input Gary Ginsberg Share this post Link to post Share on other sites
wallfish 15,934 #16 Posted June 2, 2019 Curious if it's loosing spark because of the heat, then cooling and returns. Check spark when it dies 1 Share this post Link to post Share on other sites
Gary Ginsberg 0 #17 Posted June 3, 2019 Good thought thanks. I will check. Share this post Link to post Share on other sites
ericj 1,576 #18 Posted June 4, 2019 I had an M12 that use to almost shut off when it got hot, turns out the valves where starting to hang up [ stick ] The man that fixed it said he's had some that he had to cut the valve out in pieces to get it all out good luck eric j Share this post Link to post Share on other sites
Gary Ginsberg 0 #19 Posted June 4, 2019 Thanks for the info. I did some research since it’s acting like my Model A when the capacitor goes bad. The M12 doesn’t have a capacitor or a separate coil and has a magnetic sensor I believe. Instead it has a module that contains all parts and just bolts on. Wish me luck!!! Thanks again, Gary Ginsberg Share this post Link to post Share on other sites