You've got air incursion...which wiill cause rough starts after prolonged shutdown.

There is a big air bubble in your return line from the IP to the fuel filter head.

The hoses for your primary fuel filter are split allowing air into the system,
The hose clamps should be replaced with the flat style worm gear hose clamps (Norma, etc.)
A clear Hebmuller primary fuel filter (001-477-79-01) will have bronze inserts and be much less likely to deform when the hose clamps are tightened.

The old stlye primer pump with the white handle is prone to leaks, the black pushbutton style by Bosch is a decent upgrade.

These repairs should eliminate most of your air incursion.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022