It is easy to test what would happen if you cut the Fuel Off before the Plastic Filter. Simply Clamp off the Hose/Line and see how long it takes to shut off.

If you do that the Elements are not going to be dry as there is till Fuel inside of the Fuel Injection Pump Housing and the feed hole on the Element Barrel is under the highest level of the Fuel.

Also a lot of Fuel Injection Pumps use an Electric Solenoid to cut off the Fuel. All of the older VW Rabbits and the same with My Volvo Diesel.

There is no O-ring on the Fuel Supply/Lift Pump Piston. It is a metal to meatal slip fit.

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84 300D, 82 Volvo 244Gl Diesel