According to the manual, yes you will have to bleed the system by opening the bleed plug
on the fuel filter
Again, according the manual you'll have to use the decompression lever and crank the engine
for pre 1986 engines. If your engine
has an electric pump
all you have to do is turn the ignition on.
Either way leave the bleed plug
loose until "free flow of fuel
Full disclosure: I have a M12, but it's a piece of cake to swap the fuel filter and bleed the system. Your M15 should be pretty easy, too.