Check low-pressure fuel circuit

AR07.15-G-2000DD

Check low-pressure fuel circuit

27.08.2020

Engine

900.91/92 in model 000.001

Engine

902.91/93 in model 000.001

Engine

904.94/95/96/97 in model 000.001

Engine

906.93/94/95/96/98/99 in model 000.001

Engine

924.91/93/94 in model 000.001

Engine

925.9 in model 000.001

Engine

926.91/92/93/95/97/98 in model 000.001

 Danger

Risk of explosion caused by fuel igniting, risk of poisoning caused by inhaling and swallowing fuel as well as risk of injury to eyes and skin caused by contactwith fuel.

No fires, sparks, open flames or smoking. Pour fuels into suitable and appropriately marked containers only.
Wear protective clothing when handling fuel.

AS47.00-Z-0001-01A

 Warning

Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running.

Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.

AS00.00-Z-0005-01A

Note on calculation of tightening torque when using insertion or socket tools with various effective lengths

AH00.00-P-0015-01CW

Notes on possible sources of fault in the low-pressure fuel circuit

AH07.15-N-1000-02F



Check

1

Check all fuel lines, connections and components of the fuel system for damage and leaktightness.

 Visual inspection.

If leakage is present,



Seal respective connection and tighten down threaded connection using the prescribed tightening torque.

If damage is present:



Replace respective components.

2

Clean fouled components of the fuel system on the outside.

3

Open cap of fuel tank.

4

Dewater fuel prefilter with a heated water separator and check filter element of the fuel prefilter for soiling.

Only for fuel prefilter (with heated water separator).

If severe contamination is present,



Replace filter element of the fuel prefilter.



AP47.20-G-0783DD

5

Check fuel pre-filter insert for soiling and clean if necessary.



AP47.20-G-0730DD

If severe contamination is present,



Replace fuel prefilter element.

6

Check fuel filter element for soiling.

If severe contamination is present,



Replace fuel filter.



AP47.20-G-0780DD

7

Start engine and warm up to operating temperature.

 See information from body manufacturer.
The fuel temperature in the fuel tank must be  40 °C.

8

Switch off ignition.

9

Check fuel low-pressure circuit for leaks.

Only if the engine starts badly.

AR07.15-G-2000-04DD

 Banjo bolt, fuel line (flame starting system) to banjo bolt and valve

*BA47.25-N-1006-01J

 Nut, feed line and return line to fuel filter

*BA47.25-N-1008-01J

Pressure drop in low-pressure fuel circuit

*BE47.00-N-1003-01B

Test pressure for fuel low-pressure circuit

*BE47.00-N-1005-01B

Test period for fuel low-pressure circuit

*BE47.00-N-1006-01B

 High-pressure hose

*123589042118

 Tester

*541589022100

 Adaptation parts

*541589009100

10

Measure fuel pressure downstream of the fuel filter.

Only if engine performance is poor.

AR07.15-G-2000-02DD

 Banjo bolt, fuel line (flame starting system) to banjo bolt and valve

*BA47.25-N-1006-01J

Fuel pressure downstream of fuel filter

*BE47.00-N-1001-01B

 High-pressure hose

*123589042118

 Adaptation parts

*541589009100

 Tester

*541589022100

If the fuel pressure is in the tolerance range,



do not perform further tests on the fuel low-pressure circuit.

If the fuel pressure is too high,



Measure fuel return quantity at the fuel tank.

AR07.15-G-2000-03DD

Fuel return quantity at fuel tank

*BE47.00-N-1002-01B

If the fuel pressure is too low,



Measure fuel intake pressure upstream of fuel pump.

AR07.15-G-2000-05DD

 Nut, feed line and return line to fuel filter

*BA47.25-N-1008-01J

Fuel suction pressure upstream of fuel pump at filter supply

*BE47.00-N-1004-01B

 Tester

*617589042100

 Adaptation parts

*541589009100

11

Close cap of fuel tank.

12

Perform engine test run and bleed fuel system.

 See information from body manufacturer.
The fuel system is bled automatically.

13

Switch off engine.

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1001-01B

Fuel pressure downstream of fuel filter

Idling speed

bar

4,3

Breakaway speed

bar

4,0...6,5

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1002-01B

Fuel return quantity at fuel tank

Idling speed

l/min

0,9...2,0

Breakaway speed

l/min

2,0...10,5

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1003-01B

Pressure drop in low-pressure fuel circuit

bar

0

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1004-01B

Fuel suction pressure upstream of fuel pump at filter supply

Breakaway speed

bar

­0,4...­0,5

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1005-01B

Test pressure for fuel low-pressure circuit

bar

5,0

Check values for fuel pressure

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BE47.00-N-1006-01B

Test period for fuel low-pressure circuit

min

5

 Fuel lines/hoses

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BA47.25-N-1006-01J

Banjo bolt, fuel line (flame starting system) to banjo bolt and valve

Nm

15

 Fuel lines/hoses

Number

Designation

Engine 900.9, 904.9, 924.9, 925.9, 926.9, engine 902.9, 906.9 except natural gas engine

BA47.25-N-1008-01J

Nut, feed line and return line to fuel filter

Nm

45