I just had a car come in with fire damage. The problem? The 60 year old brass float had a pin hole leak and the float was full of gasoline. If the float doesn’t float (because it is too heavy), gas keeps coming in and the fuel dumps all over the intake manifold. It only took a spark from bad sparkplug wires to set it off.
Carburetors inherently have issues related to older technology, fuel blends and age related problems. Carbs use a least one float and a needle & seat to regulate how much fuel enters the carbs. The needle closes off the fuel supply when there is enough fuel is the carb. When the float goes low, the needle allows fuel to flow until float is at the proper level. (much like your toilet) LOL.
These needles and float tension are designed for pressures less than 7lbs. Electric pumps easily make that kind of pressure and a fuel pressure regulator may be needed if used with a carb. Another COMMON problem is dirt can get in the needle. IF this happens, fuel will continue to flow & cause problems much like described above. It is important to always have a good fuel filter installed to prevent ANY kind of dirt from reaching the carb.
Even if the sparkplug wires had not set off the chain re-action above, the fuel would have continued to OVERFILL the carb and leak everywhere, possibly the exhaust and creating an even larger fire. It is important to keep all of your fuel hoses, filters, and carbs service in top notch condition.