Fix a Lawn Mower that Will Not Start When Hot - How to Diagnose & Repair

I was wondering if maybe it was a choke problem or if the gas cap had a venting issue instead of the coil. You figured it out so good job. The video is very well done and thanks for sharing with all of us.

Exact lawnmower, exact problem since new. Took to a toro dealership said they fixed it. 2nd time I used it, it acted up again. I sold it yesterday they found your video and took off the carb and cleaned it. Solved the problem.

This is EXACTLY what mine (10 years old) is doing. It's slowly been getting harder to start (and had always started on the first pull) over the past month. I am going to clean the carb and jet and see if that takes care of it. It's been a fantastic mower until now.

Brilliant video. I stripped the whole fuel system down and it still struggled to get going. After watching this I cleaned out the carburetor😁 and used Engine Starter Fluid. Works perfect now. THANK YOU

I have the exact same problem. If engine is hot and I restart in about a minute or less - no problem. Somewhere around 3 to 4 minutes off, it won't start. I suspected hot engine auto-choke issue but didn't want to waste time until I saw this video. THANKS! - to author and others. Will try carb and fuel line clean out, replacing gas cap.

I have EXACTLY the same issue with my mower. I'm going to try cleaning the carburetor. Thanks!

Thanks chief!!! Hope to do a Happy dance too after cleaning my fuel system thoroughly. From the tank, inlet hose and all of the carburetor😁

I have a rock solid Husquevarna with a B&S engine on it. It starts first pull every single time for all 6 years that I've owned it. Except.... it sometimes won't restart until it cools down JUST LIKE THIS ONE!! I can't wait to go home and see if I can fix it for good!! I'm sooo tired of having to mow my lawn in chunks day after day. Thank you good sir!

WOW!!!! THANK YOU!!!! i'm trying that tomorrow!!!!

I've got a Stihl FS 280 Brushcutter that does exactly the same . Starts and runs a treat but once it's heated up , if you switch it off before you're done , then you can forget starting it again . Now I know a good place to start . Thanks .

Yup, went through the same thing myself. I solved mine with Sea Foam in the gas. I know, now days everybody poo poos Sea Foam but it works for me. Great video.

Same issues I had. I first replaced Spark Plug & Air Filter, didn't do any better. Cheaned fuel line, carb & stuck auto choke.👍 Fixed.😃

TYSVM!! Watching & listening it felt like you were recreating moments to myself in the yard working on various things. "That's odd...." "This is a unique problem...." 🤣🤣🤣😁

My Troy Bilt does that same thing, has done it since it was new. I think it's because of the easy start automatic choke. I think it chokes it even though it's hot causing it bot to start

I am having this issue with the same kind of mower just wanted to see what your fix was. After disassembling the top of the motor checking and rechecking the coil gap and making sure the choke flapper was operating correctly. I found that the thermostat the that keeps the choke open when it's warm is causing the carburetor to not deliver fuel to restart. Therefore I need to clean the carb like you did. So there's the root of the problem, the choke system!

I have the exact same problem. Marvelous.

Great video! I been having the same issue. I thought it was just me and I was just stupid.

great job, my 9 year old Kubota zero turn is having the exact same problem.

Great video, I just went through dealing with a Briggs 725EXI lawn mower engine that always starts and runs great for as long as you want, but is dead as a dodo immediately after you shut it down even for a couple of minutes while emptying the bag. And then after about twenty minutes of cooling down, starts right up again. Replaced the coil, cleaned the carb, which helped a little for a while, and then replaced the carburetor the other day, and the problem still persisted! I had an AH-HA moment yesterday when I started to suspect that crankcase breather oil fumes that dump into the air cleaner were involved. Sure enough, after temporarily disconnecting the breather hose from the air cleaner housing, the hot start problem was eliminated! Did repeated hot starts on the first or second pull. This 725EXI has recently starting to burn a bit of oil, and you can see oil sludge building up inside the air cleaner housing at the carb inlet. Apparently the hot oil fumes are messing up the fuel mixture enough to prevent a hot start, but do not really impact a running engine, the engine always runs very strong and smooth as long as you let it after a cold start, but once hot, nothing doing! The whole situation makes sense now, once the engine has cooled down, the crankcase fumes are not present on a cold start to mess up the air fuel mixture…. I’m posting this to bring this to everyone’s attention, I have not seen anyone else make the connection of the hot no start problem to crankcase oil fumes. Looks like the engine needs a piston ring job, wonder how easy that will be, anyone out there have any experience with that? Any associated YouTube videos? Chris B. Stonington CT

Excellent diagnosis