Do you see any wet spots on the top of the IP when you push the primer? The reason i ask is that my IP is currently leaking on the first element and I get the odd bubble from that same line. I have to pull the IP and send it to a shop to replace the orings under the elements.

NExt check that the banjo bolt that that line attaches to on the IP is tight and has the aluminum washers. That bolt is also the fuel pressure relief valve. It looks like yours is a rebuildable type.

When you push the primer bulb do you hear an audible buzz? If you push it and all you hear is a light swoosh and then what sounds like air bubbles in the fuel tank you have an air lock on top of the secandary fuel filter and you need to get that out. Use a 22mm wrench on the bolt on the fuel filter and push the primer until all the air is out and you get diesel fuel then tighten the bolt. Now you should be able to push the primer and you will eventually (5-10 pumps) get the audible buzz.

Now you can glow the car and try and start it. No more than 30 seconds of starting at a time and let it cool for a few minutes in between.

__________________
Marc-André

W115 1975 300D "Geraldine"
W115 1976 300D parts/tutorial car