6.9 losing its prime
I have a 6.9 in 350 dump truck. It's a great truck starts right up first time everytime unless you let it sit for a week or so and then it loses its prime. After sitting for a week I can unscrew the fuel filter top it off and it will start right up or I can sit there and crank and crank and eventually it will start. My question is why? Any help would be great.
I have replaced the fuel pump because someone told there was a check valve in it that may have gone bad, but it didn't solve the problem. Thanks