stumplifter 8 #1 Posted May 13, 2018 Hi I have a Toro tractor it has a nameplate with Model 73542 on it. Did a tune up last year mid season, she ran fine the rest of the year. Last night did my pre-season maintenance/ inspection, sharpened blades, hooked up battery and after a squirt of starting fluid she fired right up. This morning she fired right up, mowed for about 2 hours, enough to drain the tank. Put premium fuel in from a gas can that was filled last fall. Tried to start her back up and no go, with full throttle she will crank after letting go of the key she putt-putts out (less than 1 sec), waited awhile and tried again. No throttle, cranked backfired and started running, ran for about 20 seconds and as soon as I turned the key to put the lights on she died. Waited again, after several cranks she backfired again and started running, did NOT touch the key this time for lights, tried to give her a little throttle and she died again. The two backfires were rather loud and I am concerned of damaging something. Verified battery voltage and connections. Checked fuses and cleaned contacts on fuses and relays. Spark plug was dark. Any ideas as to what I should try next? thanks! Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,509 #2 Posted May 13, 2018 The 73542 is a 520xi using a CH20 Kohler. Sounds like it is starving for fuel but the easiest thing to try is a pair of new spark plugs properly gaped. If they don't help remove them and save for the next time you want to try new plugs. Plugs can fire when out of the head but not always fire when in the head and under compression. Engine service manual. Click on the pictures Garry 1 1 Share this post Link to post Share on other sites
953 nut 51,876 #3 Posted May 13, 2018 8 hours ago, stumplifter said: Put premium fuel in from a gas can that was filled last fall. If the gas you are using has Ethanol in it there is a strong likelihood that it is the problem. When it sits it decomposes and in a fuel system it makes contact with rubber it can cause big problems. Chances are it was already decomposing in the can and has plugged the small passages in your carburetor. https://www.pure-gas.org/ Share this post Link to post Share on other sites
clueless 2,898 #4 Posted May 13, 2018 Six month old gas and you drained the tank, sounds like a carb cleaning is in order. 1 Share this post Link to post Share on other sites
stumplifter 8 #5 Posted May 13, 2018 Gary, thanks for the links! Will pick up some spark plugs. Last night I verified fuel flow to the carb. The gasket on top is showing age, I think doing a carb tear down and thorough cleaning is in order and certainly shouldn’t hurt anything. Sorry, should have clarified... premium gas in northern Wisconsin has no ethanol in it. I avoid using ethanol in everything except my car for the very reason that Richard mentioned. The tractor tank was full from last year (approx. same age as the gas in the can) ran for about two hours, parked it, tried to restart and when it wouldn’t I assumed it was in need of gas (gas gauge not functioning). So filled from gas can. I am am going to be away for a few weeks so this may end up being put on hold. I appreciate the quick replies and will report back when this is resolved. 1 Share this post Link to post Share on other sites
stumplifter 8 #6 Posted May 13, 2018 (edited) So she fired up for me just now. Not sure why I had so much trouble with a hot engine. are there any tutorials on carb tear downs? Planning on getting a carb rebuild kit, any good sources? <edit> I see the manual has a nice exploded view of the carb. Thanks again for those links Gary! Edited May 14, 2018 by stumplifter update Share this post Link to post Share on other sites
