...or some people use an oil pressure cutoff switch.
Down side of using the oil pressure cut off switch is that the engine has no/little oil pressure while cranking and therefore no fuel pumped towards the carb. You can "fix" that problem with a push button bypass to the oil pressure cut off switch.
Or you can power the fuel pump with the start terminal of the ignition switch (if you have that), bypassing the oil pressure cutoff switch, although if the carburetor bowl is full, there should be enough fuel in it to allow the engine to start.
