Diagnostic Manual, Engines, Volume 2
Hydraulic Test Program - Test (Fuel Pump Test)
Test step
DTC |
Test scope
|
Test connection
|
Test condition
|
Nominal value
|
Possible cause/Remedy
|
| 1.0 |
Fuel pumps
Delivery capacity |
N3/1
66  76
(1.25) (1.35) |
Models 124.034/036
Connect special tool fitting part no. 000 589 01 91 00 and fuel hose to diaphragm pressure regulator instead of fuel return line. Place other end of fuel hose in measuring glass.
Model 129 and 140
Disconnect fuel return line at separation point. Hold fuel hose in measuring glass.
Ignition: ON |
1 liter after maximum 35 seconds |
Check fuel lines for restrictions (kinks and dents),
Replace fuel filter,
 2.0
3.0
|
| 2.0 |
Fuel pumps
Current draw |
Connect to sockets 1 and 3 (Figure 1) |
Unplug FP relay module.
Ignition: ON |
4 - 8 A |
Fuel pump 1 or 2,
Note:
If current draw is > 8 A, also replace FP relay module.
|
| 3.0 |
Fuel pressure
after fuel pump 1 |
N3/1
66 76
(1.25) (1.35) |
Unscrew cap on fuel pump 1 (M3m1), Connect adaptor (045) and pressure gauge (043).
Ignition: ON
Read fuel pressure.
Disconnect pressure gauge (043) and adaptor (045) and check for leaks.
|
1 - 3 bar |
Fuel pressure < 1 bar:
Voltage at fuel pump 1 < 11 V,
Replace fuel pump 1 (M3m1).
Fuel pressure > 3 bar:
Voltage at fuel pump 2 < 11 V,
Replace fuel pump 2 (M3m2). |
|
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