Spitting and Sputtering

[CLSingh]

Okay, I have a Briggs and Stratton 3.75HP push mower. It was spitting & sputtering, so I cleaned the filter and replaced the spark plug (twice). It still spits & sputters until it gets near empty on gas, then it runs great until it's empty. I ran it until I got near empty and then filled it up hoping that would help... it didn't. It gets to the point that i can hear the blades hitting the grass as it's running. If I tilt the mower back on a 45 degree angle it'll run fine until I level it off. Can anyone help a guy that really doesn't have a clue on combustible motors?

 

[shiftsuper175607]

Okay, I have a Briggs and Stratton 3.75HP push mower. It was spitting & sputtering, so I cleaned the filter and replaced the spark plug (twice). It still spits & sputters until it gets near empty on gas, then it runs great until it's empty. I ran it until I got near empty and then filled it up hoping that would help... it didn't. It gets to the point that i can hear the blades hitting the grass as it's running. If I tilt the mower back on a 45 degree angle it'll run fine until I level it off. Can anyone help a guy that really doesn't have a clue on combustible motors?

My guess...the float in the carb is stuck in a partially open position.
When the tank is full it allows too much flow, and it runs bad. (the head pressure of the gas is greater with a full tank)
When the tank is low the fuel mixture is more correct and it runs good.

When you tilt it back does that make the carb higher in relation to the level of the fuel tank?

 

[CLSingh]

My guess...the float in the carb is stuck in a partially open position.
When the tank is full it allows too much flow, and it runs bad. (the head pressure of the gas is greater with a full tank)
When the tank is low the fuel mixture is more correct and it runs good.

When you tilt it back does that make the carb higher in relation to the level of the fuel tank?

Yeah.

 

[ILENGINE]

if this is the engine with the tank below the carb, with the plastic carb you need to replace the diaphragm gasket assembly between the tank and carb. It has pulled out on the intake pipe side of the carb, and pulling fuel around the edge of the diaphragm causing a rich run problem.

 

[Rokon]

You didn't say which model and type engine you had, but I found this on ebay: Genuine New Briggs Plastic Carburetor 795477 | eBay

 

[bertsmobile1]

3?? briggs will be the sprint engine , gees got to be 30, maby 40 years old.
Only difference is the older ones have a zinc carb & the modern ones have the plastic carb.
Next to the Power torque must be just about the longest production run for any engine.