Need some help...I have been having problems getting my 2000 Mercury 150 XR6 to start. I receently changed the spark plugs, fuel filter, fuel lines, primer bulb. Still won't start. Cranks good, just won't turn over. I took one of the spark plugs out and sprayed starter fluid into the block and it cranked right up and ran for 8 hours with no problems starting. Once it sits overnight it won't start again unless i spray starter fluid into the block. Any suggestions? What the heck is going on.....