Mower starts out with a full gas filter for about 25 min. then starts to sputter and barely has a trace of gas in the filter.

maybe need to put a full kit through carb. and replace few worn parts ie. float needle and seat. throttle needle and seat etc

Check everything is clean. Check the air filter is clean, check that the engine cooling fan, cutting blades and cutting deck are free of grass. Check all the drive belt pulleys to ensure accumulated grass is not jamming anything. Check the fuel filler cap is clean and the breather hole works.

Check fuel cap vent.

fuel filter may be on backwards, restricting fuel flow, if not that check that the spark plug wires are on in correct firing order, as well as the spark plug gap. (spark plugs are not always gapped for the particular application from the factory due to the multiple array of applications a particular plug can be used for)

Clean the air filter. My mower always tells me when it needs it by doing the same.

did you put the right filter and correct line size
because if the pressure of the gas is not enough it will do that

take the air filter off and rub it on your balls

check fuel pump diaphram is not streched or hard, check fuel filter for blockage, or fuel tank cap might be not venting, if none work drain and clean out carby bowl.

Hi Dave, it sounds crazy, but try this. Check your gas cap. It could be clogged, causing a vacuum to occur in the tank, and therefore not allowing the carb. to take on gas. It usually take 10-15 min. for this to occur. The next time you run the mower and it starts to stall out, loosen the gas cap and see if it begins to run again. If it does, then you know that the gas cap is clogged.

Jim

Find the fuel air mixture screw and while the mower is running turn so mower almost stops then turn them back till the moter is running smoother.Give it some throtle to see & hear how it is running