Questions ...18hp Briggs powered lawn tractor

[M.Burns]

• My usually reliable lawn tractor has decided not to run in the 0-5 degree outside temps (plowing snow). It starts, runs for less than a minute ..up to a couple of minutes then dies. Even died after running long enough to thoroughly warm up. Plugs were replaced, and it's getting spark, and air. For the short time it runs, it appears to run fine I've liberally doused the carburetor with carb cleaner. I'm suspicious of the in-line fuel filter ..the size of a quarter, with inlet on one side, and outlet on the other. Tractor is 12 years old. Filter never changed. Outside temp has usually not been a problem so maybe just a coincidence. Any thoughts?

• Also, what delivers fuel from the gas tank on an older Sears lawn tractor the engine? Is there a pump, or is it just gravity or some kind of vacuum feed?

Thanks

[Scott]

Symptoms sound like water or trash in fuel, blocked fuel filter, etc. Not sure if its gravity feed, but if it uses a fuel pump, it should be obvious. Look for mech. unit on side of engine between tank and carb.

[M.Burns]

Update: Changed the fuel filter. Put a transparent generic filter on it. Same problem. Strangely, after running the engine on just carb cleaner for several seconds, the fuel filter is NOT full of fuel like I'd expect. Temps tomorrow supposed to be in the upper 20's ..warmer in the barn. Maybe I'll find out if there is some water or ice in the line somewhere. Or might try some gas dryer. Thanks.

[Walt Conner]

I would look for crap in the bottom of carb bowl. Most 18 hp opposed flat head B&S engines had a fuel pump built into the carb. Looking directly at the carb side of the engine, there will be a metal plate 1" + by a couple of inches long just below the air cleaner and facing you. It will have a hose running in the bottom and one out the left side of the thin box for which this plate is a cover, if it is the fuel pump. Some Sears lawn tractors had a separate vacuum operated fuel pump located on the "fire wall". You should be able to located this easily by the hoses running to and from it. These engines did not have a mechanically operated fuel pump mounted on the side of the engine.

To access the carb bowl, you will need to remove the air cleaner and the screws in the top of the carb. This lifts off with the float. Take great care as the gasket will also be stuck in a nickel or so size area in the middle and gasket must come off with top and float. Try to remove without damaging this gasket as there are at least 3 variations of this gasket which are hard to tell apart and the odds of finding the correct one by its self for you carb are slim. You may have to buy a carb kit to get it. You might get by by removing the plug at the base of the carb on the right hand side, draining the gas out of bowl and blowing compressed air in there.

Walt Conner ...