Have a 1985 Mercury 9.9 that cranks on the 1st or 2nd pull but I have to pump the bulb while under way to keep it running. If I let it go dead it is very hard to crank.
Its either your fuel line primer bulb, or the fuel pump. Try swaping lines with a known good one. or just replace the bulb, if that doesn't fix it, time to rebuild the fuel pump.
