A few things to try before removing the strainer to see if it is the problem. Strainer removal can be a dirty and unpleasant job if you are not prepared.

1. Swap the IP return and supply hose in the engine bay. The idea is to bypass the strainer and draw fuel from the return line in the tank. The return in the tank in a W123 sedan is about an inch above the tank bottom so make sure you have at least 1/4 tank of fuel.

or
2. run it from a gallon jug of fuel in the engine compartment

or
3. Tee in a vacuum gauge before the primary fuel filter/lift pump. There should be no restriction, i.e. very low vacuum reading if the strainer is not clogged.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked