Small Engines (Lawn Mowers, etc.): Murray Lawnmower Stops Running, murray lawnmower, spark plug wire

Question
Hello. I have an older Murray 4.5 hp mower. I prime the engine and it starts right up, then dies after about 20 seconds. It's been running fine for several years and has had a tuneup this spring. I'm assuming it's a fuel flow problem, but I don't know how to troubleshoot it and fix it. Can you help?

Thanks.

Greg Lewis


Answer
We can try.  Sounds as though you're on the right track.

First, remove the fuel line from the carburetor and check fuel flow from the gas tank to the carburetor.  

If that's ok, then pull the float bowl off the carburetor and check to make sure the float needle and seat are working properly.  To check this, hold the float up and let it drop down and make sure that it shuts off completely (safety note: working around gasoline is very dangerous - remove any possibilities of spark....don't turn over the engine, ground the spark plug wire to the engine).  You're checking to make sure that when the float is up, it's shut off, and when it's down it's flowing into the float bowl.

If that's working okay, remove the carburetor and make sure all the vents and ports are free and clear by blowing carb cleaner through all the holes.  Reassemble and try again.

That should do it.