My motor starts and runs like a bat out of ----, then about an hour later wont start. Ball is flat or spongy. Pump it up still have trouble starting it. After it starts, runs great again. I have changed fuel lines from the tank to the bulb, also a new bulb. Can hear the electric fuel pump working, works every time. I dont know what else it could be. I was told it could be the lift pump. I would replace it, if I knew that was the problem. Also new plugs and water separator and fuel filter. Any help would be greatly appreciated. Thanks, Rick