Im not sure on that either but I’ve been using an oil pressure switch that won’t let the pump come on until there‘s oil pressure. And it turns off the pump when there’s no pressure.
Then I wire in a push button switch so with the key on you can bypass that low oil pressure switch, prime the carb and crack it off.
There is another switch that some guys recommend and I can’t think of the name of it now. I looked into it and I like the low oil pressure switch better.
