do you have to use the muffler tap for fuel pressure , or are there some other way to get tank pressure.

muffler tap for fuel pressure

You normally tap the muffler for pressure to the fuel tank. On a 4-stroke engine, there's no other source of pressure. You can't use the crankcase because it will suck air into it as well as push air out. The case needs that free flow of air in and out for the engine to operate correctly.