Check the choke. Typically these are automatic types on most new mowers. The choke is closed during cold starts then automatically open as the engine warms (think of it like a car that fast-idles in the winter, then slows down as it warms...it's not exactly the same thing, but in theory works on the same principle). What could be happening with your problem is that the choke is stuck closed or partially closed, and remains closed after the engine warms. When the choke is closed when the engine is warm, it floods the engine with fuel and stalls (and can be difficult to restart, if you can get it to restart).
To test if this is your issue, operate it until it's warm and quits. Remove the air filter and check that the butterfly valve at the top of the carburetor is open. If it's closed, open it all the way (might have to put a screwdriver, or something in there to hold it open), then try to restart it. If it's open all the way, there is likely a fuel flow restriction to the carb, or in the carb, but these problems typically cause problems running the engine hot or cold.
Two recommendations. 1. Remove carburetor, and clean with spray carb cleaner. The choke is the butterfly valve visible where the air filter attaches. Check the linkage for debris, bent or restricted linkage. After cleaning and re installation, check for free movement of butterfly choke valve. 2. Prevention. There is not a lot that can be done, but to clean the carb/choke and throttle linkage during spring tune up before first use. May require more cleaning depending on amount of use. ALWAYS USE 100% GAS, NO ETHANOL. If you must use ethanol because 100% gas in unavailable, always mix with an additive that neutralizes the effect of the ethanol. Infrequently used engines (unlike cars) that use ethanol are prone to problems because the fuel system retains water. Carburetors do not like water, cause corrosion, and repairs can be costly. For example, Someone just gave me a nice (fairly new) Bolens Riding Mower (38" B&S engine - worth about $800 ) that would not run, they just got tired of it not running right and the cost of repair shop work was about $200. I bought a $65 carb on Amazon and now I've got a nice new riding mower. They saved $.50/gal on gas and I saved $740 on a new mower...yeah, baby!
Answers & Comments
Check the choke. Typically these are automatic types on most new mowers. The choke is closed during cold starts then automatically open as the engine warms (think of it like a car that fast-idles in the winter, then slows down as it warms...it's not exactly the same thing, but in theory works on the same principle).
What could be happening with your problem is that the choke is stuck closed or partially closed, and remains closed after the engine warms. When the choke is closed when the engine is warm, it floods the engine with fuel and stalls (and can be difficult to restart, if you can get it to restart).
To test if this is your issue, operate it until it's warm and quits. Remove the air filter and check that the butterfly valve at the top of the carburetor is open. If it's closed, open it all the way (might have to put a screwdriver, or something in there to hold it open), then try to restart it. If it's open all the way, there is likely a fuel flow restriction to the carb, or in the carb, but these problems typically cause problems running the engine hot or cold.
Two recommendations.
1. Remove carburetor, and clean with spray carb cleaner. The choke is the butterfly valve visible where the air filter attaches. Check the linkage for debris, bent or restricted linkage. After cleaning and re installation, check for free movement of butterfly choke valve.
2. Prevention. There is not a lot that can be done, but to clean the carb/choke and throttle linkage during spring tune up before first use. May require more cleaning depending on amount of use. ALWAYS USE 100% GAS, NO ETHANOL. If you must use ethanol because 100% gas in unavailable, always mix with an additive that neutralizes the effect of the ethanol. Infrequently used engines (unlike cars) that use ethanol are prone to problems because the fuel system retains water. Carburetors do not like water, cause corrosion, and repairs can be costly. For example, Someone just gave me a nice (fairly new) Bolens Riding Mower (38" B&S engine - worth about $800 ) that would not run, they just got tired of it not running right and the cost of repair shop work was about $200. I bought a $65 carb on Amazon and now I've got a nice new riding mower. They saved $.50/gal on gas and I saved $740 on a new mower...yeah, baby!