I have a Craftsman lawnmower with a Briggs model 311707 17.5 hp motor that wont stay running. I just changed the starter, the air filter and the muffler. At first it wouldn't start at all so I took the carb off and cleaned everything out and made sure the fuel solenoid was working. I then drained all the gas and replaced with fresh. I pulled the plug cleaned and checked the gap. After all of that it would start, run for a couple seconds, chugging, then stop. If I held my fingers over the carb to choke it, it would fire up and I could get it to almost idle like that, but as soon as I take my fingers away, it stops. It's getting fuel, but it doesn't seem like enough. I'm stumped. Any Pro's out there have an idea?

Kevin, July 2008

i had the same problem and it required adjusting the valves and then it ran like new

Mark, April 2010

There are no diaphrams in this carb. I've cleaned and checked the float and needle valve, the valve seat for the fuel solenoid and made sure that all fuel orfices were clear thru out the body. Flanges and gaskets/o-rings are all in good shape. I do agree that it's either getting too much air or not enough fuel. I believe that I've eliminated the fuel part of that, so it leaves me thinking that it's sucking air from an obscure area. Any ideas?

Kevin, July 2008

1st thing i do with any run problem on b&s is to renew all diaphrams on the carb.u are either getting too much air (check carb/?/engine flange/gskt)or not enough fuel ,diaphrams.

caine, July 2008