[427dave]

I use to work for street rod. They are built on Club Car chassis not EZGo. No Honda engines. The older ones have a Kawasaki one cylinder engine, the new ones have a Subru one cylinder. Backfiring is not caused by fuel grade. What usually causes it is the idle adjustment screw on the carb vibrates open more. Backing out on the idle adjustment will usually stop the backfiring. When you let up on the gas pedal there is a ignition micro switch that turns the ignition off, then you press the gas pedal it turns the ignition back on so the engine will start. With the idle screw set to high it leaves the throttle plate open, fuel is sucked into the engine. Then when you hit the gas pedal to go it turns the ignition on and bang!

You should not need a new carb, they probably did not cause the problem, find someone that knows what they are doing. This sometimes it is a problem not too many people are really qualified to work on golf carts.