Yamaha Gas Golf Cart Runs Rough. The cart would not run, changed brushes in starter motor, then engine would run so rough that it was not drivable. Fuel pump was ok, fuel filter is ok, installed new drive belt no change. Need other suggestions.
Make sure it has a ground wire going from the battery (-) to the valve cover bolt.
All of these had the small ground wire in the harness break at the starter generator.
This was the fix. It would affect everything from cranking to ignition. The cart would run but not very well like it needed a spark plug.
These carts need the hotter plug. b4es or hotter ngk (hotter would be a 3)