Have a look at post #144 here;
http://www.irv2.com/forums/f123/repe...289659-11.html
I don’t know if they’ve made changes to the lift pump, yours might be different. Your injection pump pulls fuel through the lift pump. A fuel restriction gauge between the secondary filter and injection pump would show restriction in filters, screen or air being pulled into the fuel system.
I know there is a screen on the inlet to a CAPS injection pump, which I have, but yours is HPCR. Maybe someone else who has this pump can chime in.
Bill