My 3.5 hp B&S engine on my McLane reel mower dies after it warms up. It starts up just fine in choke but after the usual warm-up and after I move the choke lever back to normal idle, the engine dies. I've taken the air filter off and sprayed some carb cleaner in the carb. That seemed to have corrected the problem once and was then able to use the mower. Next time out, no such luck. Is it time for a carb rebuild?
B&S Engine Dies after warm-up
- Thread starter TomATL
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scott47429
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it sounds like its time to clean or rebuild the carb but you also may have a air leak between the carb and the engine
Thank you. What is the aluminum tube that runs from the back of the carburetor down to the engine? I noticed that it had come loose at the engine but I thought I had properly reattached it.
scott47429
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without a pic of it I'm going to say its the crank case vent it should go to the valve cover
I would take the carburetor off and clean it thoroughly after making sure to clean the tiny orifices with carburetor cleaner and a small wire ( I use twist ties ) and that should help. Usually one of those tiny holes in the carburetor throat under the throttle plate get plugged up and varnished over. You might get lucky with some carburetor cleaner and a small wire bent at a 90 degree to gently poke those holes clear of varnish. Some of those Briggs engines have carburetors on top of the gas tank, and others have the float bowl type arrangement with a fuel line going down to it from the tank. On the carb above tank types I clean where the carb bolts to the tank. Take the carb off and check the diaphragm. Sometimes they get old, stiff and won't work well. Sometimes the fuel pickup tube screens are dirty and gummed up. I've replaced several of those type diaphragms this summer. With the float bowl, it gathers water and sediments and doesn't take much to cause an engine to stumble, sputter and quit.
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Thank you for the reply. My engine has the carb on top of the tank. I think I'll just remove it as you suggest and give it a good cleaning or perhaps a rebuild. It cranks just fine and runs just fine while warming up but after I take the choke off it dies. Sounds like a good winter project for me.
That aluminum tube you mentioned is the breather tube that goes from the valve chamber to your carb. It allows the crankcase gasses to be drawn into the engine and burned.
Loose connections on either end of that tube wouldn't necessarily be the air/vacuum leaks that were suspected by a previous poster as a cause of my problem?
No, the crankcase vent tube would not qualify as a vacuum leak. If the rubber fitting on the metal tube were cracked or off it would merely let in unfiltered air, but not affect it otherwise.
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