My mower won't start?

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.

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?

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.

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?

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.