I must not have been clear in my description. My issue with the check valve not holding fuel is that when fuel is needed, there would be a (slight, I'll admit) delay in the fuel pressure until it is at the requested 50PSI.
Therefore the FPR doesn't only deliver the right pressure, it also has to deal with sub normal pressure and there lies the delay I was talking about.
This would create a lazyness in the fuel supply system.

I will, if I do, change only the pump, having the auxiliary heater, the sending unit is a pain to get and of course more expensive than the normal one.

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2002 4.6is silver on black