ME Fuel Supply Function

ME Fuel Supply Function

ENGINE 104.941,
104.943 /944 /991 /994 as of 1.8.96
ENGINE 104.995
with CODE (494a) USA version
with CODE (807) Model year 1997
with CODE (808) Model year 1998
with CODE (498) as of Model year 97 Japanese version
ENGINE 111.921 /942 as of 1.9.98,
111.943 /944,
111.946 as of 1.6.98,
111.947 /973,
111.975 as of 1.8.96
ENGINE 111.974
with CODE (494a) USA version
with CODE (807) Model year 1997
with CODE (808) Model year 1998
ENGINE 119.980 /981 /982 /985
ENGINE 120.982/ 983
ENGINE 111.945
in MODEL 208.335/435 as of 1.6.98,
202.020 /080 as of 1.9.98




Shown on engine 120
17 Fuel rail
40 Diaphragm pressure regulator
51 Pressure gauge connection
55 Fuel filter
75 Fuel tank
M3 Fuel pump (FP)
Y63 Left injectors (LH-SFI [LH])
Y64 Right fuel injectors (Y62 fuel injectors on engines 104, 111, 119)
a Connection of intake manifold vacuum

The fuel supply system must make available to the fuel injectors an adequate quantity of filtered fuel from the fuel tank, and at an adequate pressure (injection pressure), in all operating conditions.

Function
The fuel pump (M3) draws the fuel out of the fuel tank (75) and pumps it through the fuel filter (55) to the injectors connected to the fuel rail (17). The fuel pressure is controlled between 3.2 to 4.2 bar by the diaphragm pressure regulator (40) in line with the intake manifold pressure.

Excess fuel flows back pressureless from the diaphragm pressure regulator (40) to the fuel tank (75). As a result of this circulation relatively cool fuel is always available for injection (avoids the formation of vapor bubbles). The fuel injectors operated by the ME-SFI control unit, inject the fuel as a finely atomized spray into the intake passage