Mercedes-Benz Sprinter / Dodge Sprinter. Manual — part 414

INSTALLATION

(1) Install the sealing ring onto the sensor and

screw the fuel pressure sensor into the fuel rail.

(2) Tighten the senor to 60 N·m (44 ft. lbs.), back

it off 90 degrees and retighten to 80 N·m (59 ft. lbs.)
(Fig. 4).

(3) Connect the sensor wiring harness connector.

CAUTION: Care must be taken when installing the
engine cover. Assure the proper routing of the fuel
injector return fuel hose to the banjo bolt fitting in
the left rear corner of the cover. Failure to do so
may pinch or damage the hose causing fuel leakage
or a driveability concern.

(4)

(Refer to 14 - FUEL SYSTEM - WARNING).

Start engine, allow to run for a few minutes, turn the
engine off and inspect for leaks.

FUEL PUMP

DESCRIPTION

DESCRIPTION - HIGH PRESSURE PUMP

WARNING: (Refer to 14 - FUEL SYSTEM - WARN-
ING)

The high pressure pump is a fuel regulated radial

piston pump with three pistons arranged at an angle
of 120°. The regulation being carried out by the fuel
quantity valve. The high pressure pump is driven at
about 1.3 times the speed of the camshaft. Specific
moving parts inside the pump are graphite coated to
assist with the lubrication process during operation.
The high pressure pump is mounted to the front of
the cylinder head and must be replaced as an assem-
bly should a failure occur (Fig. 5).

DESCRIPTION - LOW PRESSURE PUMP

The electric fuel pump is located in the fuel tank.

The pump draws warm or hot fuel from the fuel tank
module bowl and also draws cool fuel out of the tank.
The cool fuel is drawn in and is mixed with the fuel
already in the bowl in a 50–50 mix ratio. Refer to
fuel pump module for servicing (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY/FUEL TANK MODULE
- REMOVAL).

OPERATION

OPERATION

LOW PRESSURE SIDE

The fuel supplied by the low pressure pump flows

through the fuel supply (5) at the high pressure
pump and is passed to the fuel quantity valve (11)
and the fuel pressure relief valve (9). Any air
entrained by the fuel is directed through the restric-
tor (10) through the bleed port (7) to the return flow
(6). The quantity control valve (11) controls the
amount of fuel that flows along the ring passage (4)
through the supply ports to the three high pressure
pump elements. To lubricate the plunger and barrel
assemblies when the quantity control valve is closed

Fig. 5 HIGH PRESSURE FUEL PUMP

1 - HIGH PRESSURE PUMP
2 - FUEL SUPPY TO FUEL RAIL
3 - FUEL SUPPLY LINE
4 - FUEL RETURN LINE
5 - FUEL TEMPERATURE SENSOR
6 - FUEL QUANTITY CONTROL VALVE
7 - OIL LEVEL INDICATOR
8 - VACUUM PUMP

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FUEL DELIVERY

14 - 13

(over run mode), the fuel is led directly to the circu-
lar port by the zero delivery restrictor (10) (Fig. 6).

The fuel pressure relief valve (9) limits the fuel

pressure which exists at the fuel quantity control
valve (11) to approximately 5 bar (72.5 psi). If the
pressure is exceeded, the pressure relief valve opens
and passes the fuel to the return flow (6) (Fig. 6).

The fuel pressure relief valve (9) directs a portion

of the fuel as a lubricant to the eccentric shaft (8)
(Fig. 6).

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FUEL DELIVERY

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HIGH PRESSURE SIDE

A. Filling the piston: The piston (6) is moved

down as a result of the piston spring (7). The fuel
supplied by the fuel delivery pump flows along the
ring passage (10), the valve disk and the valve spring
(3) into the cylinder. The check ball (4) prevents the
fuel from being able to flow back from the high pres-
sure passage (5) (Fig. 7).

B. Producing high pressure: The piston (6) is

moved up by the rising eccentric shaft (9) and the
fuel is compressed. The valve (2) disk shuts off the
delivery volume to the fuel supply. Once the fuel
pressure in the cylinder rises beyond the pressure
which exists in the high pressure circuit (5), the
check ball (4) opens and the fuel is pumped into the
high pressure circuit (5) (Fig. 7).

Fig. 6 LOW PRESSURE SIDE

1 - HIGH PRESSURE PUMP

7 - FUEL BLEED PORT

2 - FUEL TEMPERATURE SENSOR

8 - SHAFT LUBRACATION PORT

3 - FUEL SUPPLY TO PUMP ELEMENTS

9 - FUEL PRESSURE RELIEF VALVE

4 - FUEL ANNULAR PORT

10 - ZERO DELIVERY RESTRICTOR

5 - FUEL SUPPLY

11- FUEL QUANTITY VALVE

6 - FUEL RETURN

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FUEL DELIVERY

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OPERATION - LOW PRESSURE PUMP

When the ignition switch is on, fused battery posi-

tive voltage is supplied to the electric lift pump,
which will run for 20–30 seconds and then stop. If
the engine is cranked, the pump will begin running
immediately supplying fuel through fuel filter and
onto the high pressure pump. The lift pump and low
pressure fuel circuit operate at a pressure between
3.8 -5.5 bar (55 - 80 psi.).

Fig. 7 PRODUCING HIGH PRESSURE

1 - FUEL SUPPLY TO PUMP

6 - PISTON

2 - VALVE

7 - PISTON SPRING

3 - VALVE SPRING

8 - CAM

4 - CHECK BALL

9 - ECCENTRIC SHAFT

5 - HIGH PRESSURE PASSAGE

10 - CIRCULAR PASSAGE

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FUEL DELIVERY

VA