Check low-pressure fuel circuit · ar0715g2000b · Mercedes-Benz WIS

AR07.15-G-2000B

Check low-pressure fuel circuit

9.1.12

ENGINES 900.915 /916 /920 /921, 902.923 /924 /935, 904.927 /928 /952 /953, 906.935 /955, 924.916 /923 /931, 926.969

G07.15-3131-09

Diagram of fuel circuit

Shown on engine 904

1 Fuel delivery pump

1.2 Check valve in fuel-delivery pump

2 Fuel filter

2.1 Valve for fuel filter emptying

2.2 Continuous ventilation in the fuel filter

3 Fuel prefilter

3.1 Check valve in fuel prefilter

4 Plug-on valve in fuel feed (opened by pressure)

5 Plug-on valve in fuel return (opened by pressure)

6 Engine control unit pumps (PLD)

7 Constant vent

7.03 Overflow valve

8 Bypass from fuel feed passage to return flow passage

9 Nozzle holder combination

10 Fuel tank

30.03 Pressure limiting valve in fuel delivery pump

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B10 Fuel temperature sensor

Fuel circuit

A Fuel feed (suction/vacuum side)

B Fuel return (leak fuel)

C Fuel feed (thrust side downstream of fuel-delivery pump and fuel filter)

D Fuel high pressure side (engine control unit pumps (PLD))

E Fuel return (fuel filter emptying)

- - - Fuel passages in cylinder crankcase

Fuel lines

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Test points, test data

G Manometer test

H Fuel return quantity check

I Fuel pressure downstream of fuel filter

Idle speed:  4.3 bar

Limit speed: 4.0 up to 6.5 bar

II Fuel return flow quantity at nozzle holder combinations

Test period 5 min:

Idle speed: oil moist

Limit speed: max. only drops

III Fuel return quantity at outlet of fuel filter housing

Idle speed and limit speed:  0.3 liters/min

Fuel return flow quantity at overflow valve

Idle speed: 0.9 up to 1.7 liters/min

Limit speed: 2.7 up to 7.5 liters/min

IV Fuel intake pressure upstream of fuel pump

Idle speed: 0.09 up to 0.12 bar

Limit speed: 0.4 up to 0.5 bar

V Low pressure fuel circuit leaktightness

Test pressure: 10 bar.

Test period 5 min: pressure drop  0.25 bar

G07.15-3133-06

Diagram of fuel circuit

Shown on engine 906

1 Fuel delivery pump

2 Fuel filter

3 Fuel prefilter

4.1 Plug-on valve in fuel feed (from fuel tank)

5.1 Plug-on valve in fuel return (to fuel tank)

6 Engine control unit pumps (PLD)

7.03 Overflow valve

9 Nozzle holder combination

11 Fuel return flow duct / scavenging fuel from unit pumps

12 Return flow / leak fuel line

13 Fuel line (fuel prefilter to fuel delivery pump)

14 Fuel feed duct to engine control unit pumps (PLD)

15 Leak fuel duct

16 Pressure pipe connection

17 Injection line

A Fuel feed (suction/vacuum side)

B Fuel return (leak fuel)

C Fuel feed (thrust side downstream of fuel-delivery pump and fuel filter)

D Fuel high pressure side (engine control unit pumps (PLD))

E Fuel return (fuel filter emptying)

 	Remove/install
Danger!	Risk of accident caused by vehicle starting off by itself when engine is running. Risk of injury caused by contusions and burns during starting procedure or when working near the engine as it is running	Secure vehicle to prevent it moving off. Wear closed and close-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
Danger!	Risk of explosion caused by ignition of flammable products, risk of poisoning caused by inhaling fuel vapors or swallowing fuel as well as risk of injury to skin and eyes exposed to fuel.	No fire, sparks, open flames or smoking. Only pour fuels into suitable and appropriately marked containers. Wear protective clothing when handling fuel.	AS47.00-Z-0001-01A
1	Start engine and bring to operating temperature	 Coolant temperature about 70°C to 95°C.
2	Let engine run at maximum governed rpm	 For about 2 - 3 min.
3	Turn off engine
4.1	Tilt cab	Model 405 , model 437.42/43	AR60.80-G-0005B
4.2	Open engine hood	Model 437.46  See information from vehicle manufacturer.
5	Remove engine trim panel	Model 405.05	AR01.10-G-2405E
6	Remove air intake pipe from turbocharger to air filter	Model 405
7	Carry out visual inspection of all fuel lines, screw connections and components	 Replace damaged or leaky parts. Retighten screw connections if necessary.
8	Clean the air filter element and fuel prefilter housing (3)	Engine 900, 902, 904, 906, 924	AP47.20-G-0730B
		Engine 926	AP47.20-G-0783F
9	Replace fuel filter (2)	Engine 900, 902, 904, 906, 924	AP47.20-G-0780B
		Engine 926	AP47.20-G-0780F
	Checking
10	Open cap on fuel tank (10)
11	Test fuel pressure downstream of fuel filter (2)	 Attach test and measuring equipment to low-pressure fuel circuit.	AR07.15-G-2000-01BA
		Conduct test	AD07.15-G-7001-01B
		 High-pressure hose	*123589042118
		 Adapter parts	*541589009100
		 Testing unit	*541589022100
12	Measure fuel return flow quantity at nozzle holder combinations	 Attach test and measuring equipment to low-pressure fuel circuit.	AR07.15-G-2000-01BD
		Conduct test	AD07.15-G-7001-07B
			*BA07.15-N-1004-01E
			*BA07.15-N-1006-01E
		 Box wrench	*000589070300
		 Box wrench bit	*000589680300
		 Adapter parts	*541589009100
		 Retainer wrench	*904589010700
		 If the fuel return flow quantity is within the tolerance range, it is not necessary to conduct any further tests.
13	Measure fuel return flow quantity at engine	 Attach test and measuring equipment to low-pressure fuel circuit.	AR07.15-G-2000-01BC
		Conduct test	AD07.15-G-7001-06B
			*BA07.15-N-1007-01E
		 Connection piece	*405589009100
		 Adapter parts	*541589009100
14	Check fuel intake pressure upstream of fuel pump	 Attach test and measuring equipment to low-pressure fuel circuit.	AR07.15-G-2000-01BB
		Conduct test	AD07.15-G-7001-03B
		 Connection piece	*405589009100
		 Adapter parts	*541589009100
15	Test low pressure fuel circuit in engine for leaks	 Attach test and measuring equipment to low-pressure fuel circuit.	AR07.15-G-2000-01BE
		Conduct test	AD07.15-G-7001-08B
		 High-pressure hose	*123589042118
		 Adapter parts	*541589009100
		 Testing unit	*541589022100
16	Install in the reverse order
17	Bleed fuel system	 Crank engine with the starter for not more than 90 seconds. Wait for at least about 2 minutes before repeating attempt at starting. The fuel system is bled automatically.
18	Test vehicle power output on dynamometer	 Only after all tests or measurements have been completed and any defects corrected. If no improvement in fuel consumption or performance has been achieved, connect a fuel consumption measuring system.

 Diesel injection system with unit pumps (MR/PLD)

Number	Designation		Engine 900.91/92, 902.92/93, 904.92/95, 906.935/95, 924.91/92/93, 926.96


BA07.15-N-1004-01E	Injection line to pressure pipe connection and unit pump	Nm	35
BA07.15-N-1006-01E	Banjo bolt, fuel line to cylinder head	Nm	45
BA07.15-N-1007-01E	Banjo bolt, fuel line to overflow valve	Nm	45

000 589 68 03 00

High-pressure hose

Box wrench bit

Ring wrench

Connection piece

000 589 07 03 00

123 589 04 21 18

405 589 00 91 00

541 589 02 21 00

Retainer wrench

Tester

Adapter parts

541 589 00 91 00

904 589 01 07 00

Referenced documents

ad0715g700101b Fuel pressure downstream of fuel filter, MR (PLD) hydraulic components check
ad0715g700103b Fuel intake pressure upstream of fuel pump, MR (PLD) hydraulic components check
ad0715g700106b MR. (PLD) test of hydraulic system fuel return flow quantity
ad0715g700107b MR (PLD) test of hydraulic system fuel return flow quantity at nozzle holder combinations
ad0715g700108b Low-pressure fuel circuit leaktightness, MR (PLD) hydraulic components check
ap4720g0730b Clean filter element of fuel prefilter
ap4720g0780b Replace fuel filter
ap4720g0780f Replace fuel filter
ap4720g0783f Fuel prefilter with water separator - replacing filter element
ar0110g2405e Remove/install engine cover
ar0715g200001ba Install test/measuring equipment in the low-pressure fuel circuit
ar0715g200001bb Install test/measuring equipment in the low-pressure fuel circuit
ar0715g200001bc Install test/measuring equipment in the low-pressure fuel circuit
ar0715g200001bd Install test/measuring equipment in the low-pressure fuel circuit
ar0715g200001be Install test/measuring equipment in the low-pressure fuel circuit
ar6080g0005b
ar6080g0005b Overview - Tilt cab to repair position and tilt it back to normal position
as0000z000501a 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.
as4700z000101a 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.