Loss of fuel rail pressure

[smartynup]

My 2004 5.7 Vortec Marine Power is loosing fuel rail pressure,once the engine is shut down.My shop had done some maintenance,having to remove fuel system,and since then,this has been a restart issue.I was told there is a spring/check valve assembly,incorporated in the pump body/mount plate?
Can anyone offer any hands on knowledge with regards to my concern?

Regards,
Marty

[boatwakes]

What was the maintenance performed on the fuel rail? Pressure loss after shut down usually indicates either a faulty pressure regulator or stuck open injector. The check valve in the high pressure pump could also be the culprit but highly unlikely. Give me a little more info on what was done and I'll get you a solution.