Briggs & Stratton 6.75hp runs for few minutes then dies

[maddogandnoriko]

My neighbor asked me to see if I could get his mower to run for him and I said yes. He said the mower would fire up if he put a bit of gas in the carb then it would die. Sounded like a dirty carb to me and I proceeded to pull it off and clean it up. Sure enough the gas had started to turn to lacquer/varnish. So I cleaned it up with some gas and poked a guitar wire where I could. All looked good.

I filled it with clean gas and it fired right up. But about 3-5 minutes later it slowly wound down and died, sput sput like it was out of gas. So I refilled the gas to the tippy top and it fired up again and died again.

So I think it boils down to this...when the gas goes down about a 1/2 inch from the top rim of the gas cap it dies. The 1/2 inch is just below the 1/16 inch hole in the tank just below the gas cap. Looks like overflow or choke hold for gas or something.

I would appreciate any help I can get. And would also like to know the correct name of the little hole for overflow gas.

The engine is a Briggs and Stratton 6.75 HP with float bowl carb and no primer bulb. Fairly new with a key start. craftsman mower. Engine code#: 126T05-1071-B1 080 1956. Mower model #: 917.376480

Todd

 

[Fish]

Disconnect the fuel line at the carb and let it flow into a can, and watch the flow.

Likely your trouble is inside the carb, so you will likely be pulling and cleaning again.

 

[maddogandnoriko]

Fuel runs fine through the fuel line to carb. Any recommended guides to cleaning these carbs? Maybe I am missing something.

Todd

 

[Fish]

Fuel runs fine through the fuel line to carb. Any recommended guides to cleaning these carbs? Maybe I am missing something.

Todd

I'll need the engine's model/type/code numbers to be of much help.....

 

[maddogandnoriko]

I have included engine and mower model numbers to the end of the original post.

Todd

 

[Fish]

The main orifices you need to go at are the ones in the bowl nut {if any}, and the orifices up in the column that the bowl nut threads into, that and a good soaking may do it, but in the last several years I have had to just give up and get a new carb.

 

[EngineMan]

Clean the jet, which is the nut on the bottom of the float bowl items 117,117B,118,118A,118B on the pic..!

 

[tuit]

Went thru same thing. go to a briggs repair shop and get a rebuild kit with needle and seat then search you tube for Briggs carb overhaul. Don't half *** it by not replacing needle and seat, i had carb off two or three times until i finally replaced them. I used the back side of a drill bit the same size as the rubber seat to push it in. Started and didn't die afterwards.
Neighbor had same problem with new 2 week old Honda, 2nd time to use it. said he had been trying to start it for 3 hours and just started tearing it apart before I got home. Told him to pull carb off, had about 1/4 inch of fine sand in float bowl and all the jets plugged solid. He said he bought a new gas can when he bought the mower two weeks earlier and it was clean. Pulled gas tank off and removed the small strainer inside the supply hose, both were clean- no sign of any sand. Also removed the gas shut off valve, no sign of any scraping on the plastic, sand didn't go thru shut off valve. Had to be casting sand from when they cast the aluminum body since no dirt or sand was any where else in the fuel lines. Used a twist tie wire and spray carb cleaner to clean out the jets and passages the blew out with compressed air- started and ran fine afterwards.

 

[maddogandnoriko]

Thank you all for the help. There was a tag on the machine, like a luggage tag...so I assume it was either pawn shop or repair place.

Either way...the float needle seat was not pressed in enough... So the float was sitting on the bottom of the bowl and not allowing enough fuel in fast enough, I think. So when I had the carb off and turned it upside down the float sat at nearly a 45 degree angle. I took off the carb on a parts mower and the float sat almost horizontal.

Busted the seal "inspecting" it...so off to the the parts shop. Thanks again for the help.