Fuel System

When converting to an M57 engine, it’s easy to mix up the fuel feed and return lines. Remember this simple rule: the feed line to the high-pressure (HP) pump is always the port closest to the front of the engine. Always trace this pipe back to confirm you’re connecting the feed line correctly.

You can simplify your conversion’s fuel system as shown in the diagrams below. We use the same inline pump from the donor vehicle. Unless you have major restrictions, this pump can easily draw fuel directly from the tank and doesn’t need a separate regulator. We recommend and supply Pierburg pumps in our shop.

M57 184/193

This fuel circuit contains the original filter with the pressure sensor which should be connected.

M57N

Later engines with solenoid injectors are only slightly different, they just use an inline filter rather than one with a pressure sensor:

*Although some factory fuel systems (like in the E60) use an in-tank pump, we find the earlier style of inline pumps works well.*

M57N2

M57N2 is generally the same an M57n engines, with one key difference, the injectors.

Engines with piezo injectors require specific back pressure in the injector spill line. There is usually a factory-fitted restrictor in this line; make sure it remains installed.

Again, we find the inline fuel pump works well for this set up.