Engine cranks but does not start

It turns over fine and runs like a champ but getting it to start is the trick. I thought it was the fuel pump and/or fuel filter so both replaced twice! But nothing helped. I reprime multiple times and can even smell gas at times if primed enough but it just keeps turning over but never will crank like its not getting gas or something. But if it was the fuel injector it wouldn't run right when driving so I know its not that. If its the lines I would smell it or still notice it when driving. The thing is though at times it will crank on the first prime but has to turn over a bit but then others it takes ten minutes to get it to crank. I need this fixed before my starter goes out or worse.