B&S 17.5 3100 popping/butterfly fluttering

[K5Chris]

Hi, I have a Poulan Pro riding mower from Home Depot that is practically brand new (about 3 months). We took the deck off, and use it to tow 4,000 lb cars around the parking lot. This is replacing a John Deere D100 that we used for 4 years with no issues, until it failed.

Engine: B&S 17.5 31R907

Here's my problem, it starts fine and idles smooth. About 1/2 throttle and up, it pops out of the exhaust like a misfire. It may have been doing this from day 1, if not, it started in the first week. When I watch the butterfly valve on the carburetor, the governor allows it to flutter rapidly, up to the point of briefly closing the valve. When I hold the butterfly valve open, it runs smooth. I tried slightly increasing the tension on the governor, with no luck (I put it back in stock position). Can this be a problem with the governor internally, incorrect valve adjustment, or carburetor? We use only good 93 octane fuel, and it's used almost every day.

Any advise is greatly appreciated.

 

[bertsmobile1]

If you hold the govenor at a position and the engine runs smoothly for a few minutes then yes you have a problem with the govenor.
If the mower is new take it back.
If it has a hydro drive you will kill it no time flat using it for a tow motor.

 

[K5Chris]

Thanks. It is a 6 spd manual. That is the whole reason I bought this one. It's the only manual I could find.

 

[Tinkerer200]

You may want to check the static governor setting. Loosen clamp holding the governor arm to the governor shaft coming out the side of the engine, move carb butterfly to wide open, note which direction the arm moves to do this, turn the shaft fully in the same direction and re-tighten the clamp. But best thing to do is return it under warranty as said above lest you void warranty messing with it.

Walt Conner