Fuel pressure at shut-off

[LateFan]

'86 325es.

Installed a new FPR, starts right up, fuel pressure is steady 31-32 psi.

At shut-off, it maintains pressure in the 30s for an hour or so, starts dropping, and the next day it's 0 to 5 psi.

Does this mean the check valve in the pressure pump is going?

Thanks -

[atldohc]

if you have no external leaks then yes. either that, the fpr, or a fuel injector might have a small leak.

[LateFan]

Rebuilt injectors, new FPR, no leaks.

Ordering a new pump.

Thanks!