Guys I know this is not a John Deere Lawn Tractor thread but I got to get the lawn mowed before I ride the Sling. The mower won't run unless I hold the choke fully engaged. It runs fine that way as soon as I let go it starts stumbling bad. I suspect it is the carburetor but some of you guys were born with a wrench in your hand I believe. I have replaced the air filter and the fuel filter is one of those glass ones and looks clean.
Typically a choke does just what it says. It cuts of the air flow thus enriching the fuel/air mixture. Some systems add fuel to enrich but most of the basic engines cut off the air supply until the engine warms up to proper running temperature and then requires less fuel to achieve the correct ratio for proper atomization.
Typically there are three fuel Jets in most carburetors with the pilot jet used at low throttle range. This jet has the smallest opening and typically clogs when stored over time. If the engine runs with the choke on it's telling me it's deprived of fuel and thats why you need to keep the choke on restricting air compensating for the loss of fuel through the piolet/starter jet. My experience tells me it's a big probability the piolet jet is clogged and need to be cleaned.