Danm1441 10 #1 Posted March 4, 2019 I was plowing snow this morning with my tractor which is a 1988 312-8. The engine is a Kohler 12. The snow was very wet and heavy. The tractor seemed to be running OK but after I had been plowing for 15-20 minutes the engine stopped running and acted as if it had run out of gas. I checked and there was still about 3/4 of a tank left. I tried restarting the engine and it started, but after a few minutes it did the same thing. I had to stop using the tractor and shifted to using a snow blower. About a half hour later I tried restarting the tractor and it ran. I was able to drive it back into the garage. Any idea what the problem might be? Thanks. Share this post Link to post Share on other sites
pfrederi 17,116 #2 Posted March 4, 2019 To be sure your engine is a magnum 12 correct? The ignition system in those is very reliable however if some snow got on your plug wire and melted it could be an issue. Do you have a spark plug tester?? Share this post Link to post Share on other sites
rmaynard 14,861 #3 Posted March 4, 2019 Sounds like the vent in the gas cap is clogged. If the engine runs with the cap loose, then stops shortly after it's tightened, you have a clogged vent. 2 1 Share this post Link to post Share on other sites
Danm1441 10 #4 Posted March 4, 2019 The engine is a Magnum 12. I do not have a spark plug tester, but I do not notice any sign that water got under the hood and wet the plug wire. It was not raining or snowing while I was plowing, so I don't think that could have been the source of water. The gas cap was replaced recently with a new cap. Can the vent of the cap become easily clogged? Also, the new gas cap seems to fit more tightly than the old one. Could that be a problem? Thanks. Share this post Link to post Share on other sites
953 nut 51,464 #5 Posted March 4, 2019 I have encountered the same symptoms on two of mine and both times it was the vent on the gas cap. As fuel is removed from the tank a slight vacuum develops in the tank and without being vented it will prevent the fuel pump from removing any more fuel. Try what Bob suggested, back off the cap a bit and see if it helps. 1 Share this post Link to post Share on other sites
Danm1441 10 #6 Posted March 4, 2019 I will try backing of on the cap to see if that does it. That would be great if the solution is that easy! I need it to be spring or have the tractor functioning as my old back isn't what it used to be and the tractor makes a big difference. It's fun to drive too! (but I don't admit that to my wife) Thanks guys. 1 2 Share this post Link to post Share on other sites
The Tuul Crib 7,332 #7 Posted March 4, 2019 3 hours ago, rmaynard said: Sounds like the vent in the gas cap is clogged. If the engine runs with the cap loose, then stops shortly after it's tightened, you have a clogged vent. Share this post Link to post Share on other sites
Rob R 951 #8 Posted March 4, 2019 Sounds like a fuel delivery problem to me chk lines (if old replace), tank, filter, fuel pump and lastly the carburetor...… wouldn't hurt to make sure the your getting spark to the plug this should be easy since you apparently have no issue recreating the problem. Share this post Link to post Share on other sites
Danm1441 10 #9 Posted March 10, 2019 I took a look at the gas cap yesterday. It is a relatively new gas cap and the vent did not appear to be clogged. I loosened the cap a bit , started the tractor up and ran it for awhile. The problem did not re-appear. Hopefully that's it, but we'll see. Thanks to everyone for your input. 1 Share this post Link to post Share on other sites
pacer 3,159 #10 Posted March 10, 2019 I recently bought a new 'Kelch" cap (the one that will read fuel level) , having bought several of these I never thought about the venting as all others were vented. Well, after several events of engines unexplainably quitting - and I was a looong was from the shop, I loosened the cap and get a very noticeable 'whoosh!' OOOOK!! theres the problem! Leaving the cap loose I drove back to the shop and drilled a tiny hole in the cap -- and problem solved 2 Share this post Link to post Share on other sites
Danm1441 10 #11 Posted March 10, 2019 Well, that's exactly the type of cap I recently replaced the old one with. After I had the problem, I opened the gas cap. I didn't hear a "whoosh" but it did feel like a vacuum had occurred. I think your solution sounds good pacer. How big a hole did you drill? 1 Share this post Link to post Share on other sites
pacer 3,159 #12 Posted March 10, 2019 1 hour ago, Danm1441 said: How big a hole did you drill? Ahh ... not real sure but probably 3/32 - 1/8" 1 Share this post Link to post Share on other sites
Danm1441 10 #13 Posted March 12, 2019 Pacer,I went back and checked the cap and it was a Kelch. Sounds like these folks may have a manufacturing glitch or the caps are produced to fit different applications and not all of them need a vent. I am going to try the hole drilling you suggested. Did you drill the hole on the top of the cap or through the port that look like it is supposed to be a vent? Thanks. Share this post Link to post Share on other sites
