Kevin H 3 #1 Posted June 29, 2021 I have a Toro 520xi with the Kohler Command 20hp. The last 2 seasons it has had this problem. When cutting it seems like it drops a cylinder and you have to turn the deck off and choke it to stay running. Watch the video and tell me what you think. https://youtu.be/N4gUa3-JPQE Share this post Link to post Share on other sites
Handy Don 12,251 #3 Posted June 29, 2021 (edited) Starving for fuel. Fuel filter clogged, gas tank cap vent clogged, pinched fuel line, fuel line hole letting it suck air, fuel pump pulling air or failing, sticking float in carb Edited June 29, 2021 by Handy Don 1 Share this post Link to post Share on other sites
pfrederi 17,741 #4 Posted June 29, 2021 Just a nonexpert thought (my newest WH is 20 years older than yours) These newer uints have an anti-backfire valve. It is shuts off fuel to the the carb when it is turned off (no voltage). Your charging system light is on frequently. Maybe your voltage is dropping so much the solenoid in the valve cannot over come the strength of the closure spring.and she starves for fuel. You might hook up a mulltimeter and see what the voltage is when running and if it drops when she starts to stumble... 2 1 Share this post Link to post Share on other sites
oldlineman 1,481 #5 Posted June 29, 2021 (edited) Your battery light is on, maybe low voltage and coil voltage is dropping to the point that can't fire both plugs. I would check charging system. Like Paul my experience is with older horses but what he said makes sense also. Bob Edited June 29, 2021 by oldlineman 3 Share this post Link to post Share on other sites
953 nut 55,360 #6 Posted June 29, 2021 I agree that your engine is suffering from fuel starvation. If you have been running gas with ethanol please STOP. Ethanol will kill a fuel system. https://www.pure-gas.org/ 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,060 #7 Posted June 29, 2021 1998 model? Garry Share this post Link to post Share on other sites
Kevin H 3 #8 Posted June 29, 2021 I don't have a carburetor solenoid on this motor. The battery voltage checks out, these have some type of comparator that turns the light on. I have a lawn mower sales/repair place near me, but they don't sell Toro and aren't familiar with it. I don't know who to trust and don't have a trailer to transport it. I have had the carb off a few times, changed the fuel line and still does it. Share this post Link to post Share on other sites
Kevin H 3 #9 Posted June 29, 2021 5 minutes ago, gwest_ca said: 1998 model? Garry Yes, 1998 Share this post Link to post Share on other sites
Kevin H 3 #10 Posted June 29, 2021 Wow, that document was great! I was going to pull the fenders off again to check the tank and replace the fuel line to the filter. One time last week it leaked gas out behind. I figured the gas tank was full and vented. Share this post Link to post Share on other sites
Zeek 2,286 #11 Posted June 29, 2021 Like someone else said, I'd loosen the gas cap. If it runs fine, your vent is clogged. If it keeps doing it, I'd junk the carb and get a new one on Amazon. I'm guessing it's either this one or this one. I just bought one last week for a Kohler Courage 26 HP that wouldn't stay running for after three carb cleans. Now it's runs great! Share this post Link to post Share on other sites
Handy Don 12,251 #12 Posted June 29, 2021 (edited) 24 minutes ago, Kevin H said: these have some type of comparator that turns the light on. That circuitry is built into the voltage regulator (which has several connections (including one to the indicator lamp) compared to the three connectors on older engines). There is another thread that mentions this on a 520xi, I believe. You may want to replace the VR since the indicator being on is not good. Edited June 29, 2021 by Handy Don Share this post Link to post Share on other sites
Kevin H 3 #13 Posted June 29, 2021 (edited) Looks like a mouse has gotten the best of me. The first picture is the end of the vent line. I will replace the fuel line. Should I replace the sender gasket too? I hope they are still available. Edited June 29, 2021 by Kevin H Bad text 1 1 Share this post Link to post Share on other sites
Handy Don 12,251 #14 Posted June 29, 2021 (edited) 3 hours ago, Handy Don said: Starving for fuel. Fuel filter clogged, gas tank cap vent clogged, pinched fuel line, fuel line hole letting it suck air, fuel pump pulling air or failing, sticking float in carb Yes! Annoying as all get out, but at least a relatively easy and inexpensive fix. Unless I saw signs of deterioration or other damage to the sender gasket, I would let it be. Its job is to keep debris out and sloshing gasoline in. If it is doing that, it's good. Edited June 29, 2021 by Handy Don 1 Share this post Link to post Share on other sites
oldlineman 1,481 #15 Posted June 30, 2021 Yep thatil do it as said above easy and cheap fix glad you found it. Bob Share this post Link to post Share on other sites
Kevin H 3 #16 Posted June 30, 2021 Glad I decided to remove the shut off valve... Share this post Link to post Share on other sites
Crazyredhorse 295 #17 Posted June 30, 2021 yea sounds like fuel.maybe float not letting enough gas in?starving Share this post Link to post Share on other sites
