jimbo1364: I'm assuming you have the "old style" canister secondary fuel filter, where you remove the lid and replace the element. The hose out the bottom of the canister is the injector pump inlet. Fuel goes from the primary filter to the fuel pump to the side of the canister (dirty fuel) to the bottom of the canister (clean fuel) to the injector pump. The "plug bolt" on the bottom side is where you can drain the sediment that accumulates on the dirty side (between changes, and this is why I like this filter setup). The secondary filter overflow should be in common with the injector and injection pump overflows, and turns into the tank return line, possibly all at a "manifold" at the canister lid, probably the injection pump overflow is a separate fitting at the lid top.

Check the tank strainer first, just like P.E.H. says. Then loosen the secondary filter vent "plug bolt" on the lid, near the tank return line (not the long center lid clamping bolt). Then hand pump until fuel runs out the vent. Wipe it dry and let it sit 15min or so (lets the bubbles settle down - inside the lid). Then slowly hand pump until fuel runs out again. You've mostly filled and bled the canister at this point, but there may be air bubbles elsewhere. Button up the vent. Then hand pump again, and use a wrench to tap the injection pump side, injector pressure pipes, and that secondary filter overflow manifold. This is when you listen for and may not hear that "buzzing" - I don't hear that well. Check for leaks while you're pumping and tapping. Hand pump and tap for 30min or so - air bubbles in the injection pump or pipe bends can be stubborn. ANY leak is bad and needs to be fixed.

Hopefully you've used new seals on the glowplugs and injectors - this is a compression engine. Were the new injectors checked and balanced with each other before installing? Reinstall the glowplug wiring properly? If it ain't broke....

__________________
daBenz - 1970 220D