More often than not, golf cart backfiring is caused by the throttle plate inside the carburetor being slightly open. This allows fuel to flow into the cylinder before the ignition system is activated to produce a spark for combustion. Instead of igniting a small amount of fuel when working properly, a larger amount collects and you get a significant explosion, which is called a back fire. For the fuel and ignition systems to work properly together, the spark should be in the cylinder via the plug prior to fuel gets there.
In almost all cases, whether it is a 2 cycle or 4 cycle engine, golf cart backfiring is caused by the accelerator cable being out of adjustment at the throttle plate of the carburetor. This problem has a relatively simple cure.
With the ignition key in the OFF position and the seat completely removed, press the accelerator pedal down. You will hear a low, almost inaudible “click” from the accelerator micro switch. Depending on the golf cart brand and model, this accelerator micro switch may be located around the pedal itself or possibly mounted to the inside of the front wall of the engine compartment. Once you identify where your accelerator micro switch is located, press the accelerator pedal down again and listen for its click, while looking at the carburetor throttle plate.
For proper symbiosis between the fuel and ignition systems, the accelerator micro switch must click BEFORE the throttle lever of the carburetor moves. The accelerator cable may move through the plate, but the plate itself cannot move prior to the micro switch click. If you find the throttle plate moves prior to the click, you will need to make adjustments.
The needed adjustment to remedy golf cart backfiring will vary between manufacturers and year models. Some accelerator cables have a wire which slides through the throttle plate and held in place with a cable nut, in which case you loosen the nut, press the throttle plate closed and re tighten If there is a cable spring, be sure it is compressed against the plate in this process. Be sure to double check your adjustment against the micro switch click for good measure.
Other golf carts may not have accelerator cables, but rather system of rods between the accelerator pedal and the carburetor. In this case, you generally have to adjust the length of the last accelerator rod before the carburetor to allow the throttle plate to close fully. As above, always be sure to check your adjustment afterwards to ensure proper function.