Is the check valve in the pump or in the plumbing external to the pump?Ordered a new fuel pump. Have been noticing an extended crank, especially after sitting. Tested the fuel pressure and it drops to zero almost immediately after turning off the Jeep. Pulled the injector rail just to make sure and didn't see any leaks. I'm kind of glad it wasn't the injectors (PO installed new Bosch 4-hole) but annoyed I'll have to drop the tank.