General Question

1sonja___'s avatar

My mower won't start?

Asked by 1sonja___ (12points) June 5th, 2011

Our B&S 3.5 mower starts after setting overnight but then dies after about 5 minutes. We tried Start your Engine but it is still doing the same thing. Can you help?

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5 Answers

Tropical_Willie's avatar

Runs but stops after a few minutes, usually means a clogged fuel in between tank and carburetor. When was the fuel put in? months ago? Drain and refill after checking fuel line for restrictions or debris.

woodcutter's avatar

It it an old machine? Usually if there is an obstruction in the fuel line it will run for a few seconds, not a few minutes.The primer bulb will pump enough fuel in there to get it going but it will burn up very quickly, like in about 5 seconds. If it is a machine with a bad piston ring it might start and run when it’s cold but it won’t run very long. I’m assuming the obvious things were checked first like air filter, fuel filter if there is one, the spark plug?

YoBob's avatar

Ok, heres the playbook for dealing with persnickety lawnmowers.

1) Clean the air filter. Eventually these get clogged up and can’t suck enough air in to support combustion.

2) Make sure that the connection to the spark plug is good. Often times lawnmowers run poorly because they aren’t getting enough juice to produce a good spark.

3) Make sure the spark plug itself is ok. they usually go bad after a couple years use.

If none of these work it’s time to get drastic. Check the fuel lines for clogs, disassemble the carburetor, etc…

Good luck.

woodcutter's avatar

Do 3½ hp Briggs even have fuel lines? I thought the carb sits directly on the fuel tank itself using a diaphragm to pump the gas?

john65pennington's avatar

Each year, the gasoline in your lawnmower should be emptied and the gas tank cleaned. Any leftover debris from the previous lawn-cutting season, could be left in the tank and clogging its fuel line.

Remove all old gasoline and fill with fresh.

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