Optimal Diesel Fuel Routing.
Over the past few months, have helped a half dozen or so people reroute their fuel systems for easy bleeding and optimal delivery.
It's simple and effective and has always been successful for me, so have shared it here to hopefully help members and provide a thread to point others to when they ask for the same advice.
Fuel tank feed, sedimenter, 12V electric fuel pump, engine lift pump, fuel filter, injection pump (IP), IP return joins with injector spill over line and routes back to the fuel tank return line (separate line from the fuel tank feed).
That's it... very simple.
A lot of the 2.5, and 2.25 diesels, most Mercedes, Peugeot, Iveco, Diaharsu and other diesels loop the return line back to the fuel filter that is generally positioned on the suction side of the lift pump. This makes bleeding the air very very very difficult. If you think about it, looping the fuel also loops all the air in the system. When you send the return line from the IP straight back to the tank, it pushes all the air out of the IP and sends it back down the return line. With the 12V fuel pump, air purge is automatic. The system becomes self bleeding. The other benefit is that the IP doesn't run dry. Fuel lubricates critical parts of the IP and trapped air means less than full lubrication or perhaps none at all.
The Isuzu 4JB1-T does not even have a lift pump, but a 12V fuel pump provides a self bleeding fuel system.
Hope this helps those of you who have difficulty bleeding your fuel system or are doing an engine conversion and need a suggested route for your fuel system.
Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)