birdog9999 0 #1 Posted June 2, 2014 I have a Toro wheel Horse 312-8. I bought it new in 1992. It has been a work horse and I really love it, 23 years with no trouble except some minor repairs. Last summer it started stalling once it got hot. Took it to the shop and they said it needed the carb. to be adjusted. It worked the rest of the summer with no problems. It worked all early spring with out a hitch, until about a month ago when it started stalling once it got hot. I took it back to the shop this time they said it needed an ignition module they replaced the module spark plug, and fuel filter(which I had already replaced). After $185 I got it home and it was still doing the same thing. Since I have replaced the carb. with a brand new one, and checked the fuel pump. When I started it up it purred like a kitten. I mowed for about fifteen minutes and it started stalling again. I am at a loss at this point don't know where to go from here. Anyone have any thoughts? Toro Wheel Horse 312-8 Engine Magnum M12S Spec 471527 Build 1992 Share this post Link to post Share on other sites
Wishin4a416 2,190 #2 Posted June 2, 2014 Just something else to check out. Mine did exactly the same thing years ago and it was a sticky exhaust valve. I am not good at electrical issues so I will leave that to someone else. Good Luck and Welcome to Red Square. Share this post Link to post Share on other sites
Sparky-(Admin) 21,254 #3 Posted June 2, 2014 Vapor lock ?? Have you tried mowing with the gas cap loose? Mike........ Share this post Link to post Share on other sites
Fordiesel69 259 #4 Posted June 2, 2014 1. Check for spark when it dies. 2. Disconnect fuel supply hose to carb and crank over. It should be pulsing a decent amount of fuel. 3. Listen to the starter, does the engine sound like it is spinning over without full compression? Report back with your findings. Share this post Link to post Share on other sites
birdog9999 0 #5 Posted June 2, 2014 Sparkplug is new replaced by dealer. Also ignition module, if these were the problem I would think the dealer would have fond it(just my opinion). I bought a new fuel pump(everything I see says its the right one) but the lever seems to be the wrong angle as best I can tell it is not touching the cam, so I put the old one back on it is pumping fuel, but I'm not sure it is always supplying enough gas. The engine starts on a dime and runs fine as long as I don't try to mow. If I chock it sometimes it will smooth out for a for a short time. I am convinced that it is a fuel problem but without getting the right fuel pump I can't be sure. I will check the fuel cap haven't checked that. Any thoughts on checking the sticky exhaust valve. Also I don't see how it could be a vapor lock since it is pumping fuel. I really don't want to replace this mower but I have to have a working mower, my neighbor has been mowing my lawn and I can't expect him to do it for ever. I don't want take it back to dealer and pay another $200 to be in the same situation would rather spend that money on a new tractor. Share this post Link to post Share on other sites
Fordiesel69 259 #6 Posted June 2, 2014 Stay away from the dealer. Most will throw parts at it because they cannot reproduce the problem. Replace the fuel pump with a genuine kohler plastic body pump. You will get a long time out of one beleive it or not. How many hrs are on the engine? The only way to check the ex valve is to take it out and check for signs of scoring on the stem, and checking the clearence. Share this post Link to post Share on other sites
birdog9999 0 #7 Posted June 2, 2014 Can't say how many hours because hour gage stopped working however, the tractor is 23 years old and the plastic pump has been working all that time(not sure it's not working now). I did buy a Kohler pump but for some reason the arm is not the same as the old one even though everything I can find says it is the right pump. I'm trying to work with the pump supplier to to correct the situation. Share this post Link to post Share on other sites
birdog9999 0 #8 Posted June 2, 2014 Well problem fixed. I pulled the fuel line from the fuel tank and no gas was coming out took the air hose and blew it out and fuel started to run but very slowly. took the valve out cleaned it and the tank put it back together and she is purring like a kitten. Thanks for the help. Share this post Link to post Share on other sites
Fordiesel69 259 #9 Posted June 3, 2014 I thought it was a fuel problem, as it has been on all my K series kohlers. You may want to replace the fuel shutoff valve if the screen cannot be cleaned. I have needed to replace pretty much all of mine. Honestly though, plan on a fuel pump in the near future. The magnum plastic ones are good, but not past 20 yrs or so...... Share this post Link to post Share on other sites
JC 1965 1,530 #10 Posted June 3, 2014 I just replaced the fuel pump on my 312-8 ( with 12hp mag. ) with an electric fuel pump. Share this post Link to post Share on other sites
birdog9999 0 #11 Posted June 3, 2014 What fuel pump do you use? I ordered the 47 559 11S and it does not work on my engine the arm has a different angle and it doesn't ride on the cam so it never pumps any gas. Yet everything I see says it is the right pump. I am wondering if the 47 559 04 might have the proper arm. Share this post Link to post Share on other sites
Wishin4a416 2,190 #12 Posted June 3, 2014 Good news! Shes back up and runnin. Share this post Link to post Share on other sites
