Tried the check valve and it made no difference. There appears to be a 1 second timer that controls the pump at start up. If I could over ride that the pump should run until the PSI is up and the rail is full?

Can I hot wire the fuel pump with a momentary 12 v supply to "load" the rail before starting?

Why not run a 12v line through a momentary switch to run the pump before starting to fill the rail with enough fuel pressure?

Tried the key on off, NG. Does bleed off in 20 min, not every time but mostly so.

the local Volvo dealer diagnosed fuel pressure loss over night as the reason for hard starting, a leaking check valve at the pump. They want $1500 to replace the pump which works fine. Car runs well once started. Why can't I install a Russel check valve inline between the injector rail and the pump ...