I have a pretty high incline on my driveway . If I park my truck pointing up the incline it looses it prime and takes a long time to start. If I back in and the truck is pointing down the incline it starts right up. Also , there seems to be a small leak of fuel. There is a small spot the size of a half dollar every time I park on flat land or pointing up on my driveway. Leak is near the back of the head area. It's not the fuel pump or fittings, I checked those. Is there
another fitting or check valve in that area I should check ?

 

return lines from the pump are leaking air and loosing prime. easy to replace

 

Any pictures or diagrams available , so I can see where they are and how
to change / tighten them.