Fuel feed system, principle
P0006025
Fuel is drawn up with the aid of a feed pump, via a
check valve, first through the strainer in the fuel gauge
sensor, then through the auxiliary
(1)
pre-filter (
1
), then
up through the ECU cooling loop (
2
) and then down
to the fuel filter housing. Here the fuel passes a check
valve (
3
) and the pre-filter with water separator. The
check valve function is to prevent fuel from flowing
back to the tank when the engine is shut down, and
during hand pumping.
The feed pump forces fuel to the fuel filter housing
through the main filter and up to the cylinder head
longitudinal fuel channel via a check valve (
9
). This
channel supplies each unit injector with fuel via a ring-
shaped channel in the cylinder head around each
injector. The overflow valve (
11
) regulates fuel feed
pressure to the injectors.
Return fuel from the cylinder head fuel channel
passes through the overflow valve (
11
) back to the
fuel filter housing.
Return fuel is mixed in the fuel filter housing through
channel with fuel from the tank and is drawn on to the
feed pump inlet (suction side).
There are two valves in the fed pump. The safety
valve (
7
) allows the fuel to flow back to the suction
side when pressure becomes to high, e.g. if the fuel
filter is clogged. The check valve (
6
) opens when the
manual fuel pump (
4
) is used, to make it easier to
pump up fuel by hand.
There is also a venting valve (
12
) located in the fuel
filter housing. The fuel system is vented automatically
when the engine is started. Any air in the system flows
together with a small amount of fuel back to the tank
via a line.
There is a venting nipple (
10
) on the front level pipe
for venting a completely empty system.
1) Option.
20-0 Engine Information, General
7748841 06-2010
91
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