Small Engines (Lawn Mowers, etc.): Briggs and Stratton intermittent varoom, briggs and stratton, lawn mower engines

Question
-------------------------
Followup To
Question -
Eric,

My Briggs and Stratton lawnmower has a problem.  I bought it new in Summer 2004 for $100, 3.5 hp, and have mowed my 70 x 130 yard with it several times up to now with no problems.  The 2nd time I mowed this spring (yesterday), I mowed about 4 rows then it started acting up. It would pick up rpm, then sputter, then pick up rpm, then sputter, and continue this non stop. My gas usage doubled.  The throttle, choke, and wheel height are all automatic.  I changed the spark plug, put in new gas, sprayed gumout down the carb, took off the air cleaner, the oil level is fine, all with no effect. When I tilt the mower to where the front wheels go up, the intermittent varoom smoooths out somewhat.

What can I do? Does this sound like a clogged carb? Can I fix it? Maybe the floats need adjusting? I am new to dismantling lawn mower engines but I would be game to giving it a try. I did put the lawn mower together myself.  I did notice the linkage below the air cleaner did go back and forth and back and forth, and it didnt matter where the linkage was, the sputtering continued, and in some cases the mower died.

I barely made it through mowing a couple days ago and this was annoying.

Thanks and any advice is appreciated,
William Edwards
Answer -
Can you tell me if you have a float style carb with a rubber fuel line or do you have a carb the is bolted directly to the fuel tank?

Let me know.
Eric

Eric,

The carb is bolted on top of the gas tank.

Thanks,
William

Answer
These carbs are more difficult to fix.  Most engine surging is caused by a carb problem.  Normally we clean the carb with compressed air after we dis-assemble it.  Once the carb is clean we put it back on the engine and check the engine RPM with a tachometer.  If the engine speed is correct and the carb is clean we replace the governor spring.

Does this help?
Eric