| Test Step |
Test scope |
Test connection |
Test condition |
Nominal value |
Possible cause/Remedy |
| 1.0 |
Fuel connections |
|
Check for leakage.
|
|
|
| 2.0 |
Check for ease of movement of air flow sensor plate (4) with lever (1) and control plunger (2) in fuel distributor (  32 , Figure 1). |
|
Switch on ignition briefly to build up fuel pressure.
Depress air flow sensor plate (4) by hand (Figure 1).
Release air flow sensor plate (4) quickly. |
Uniform resistance should be felt during its entire travel.
No resistance should be felt since the slow to react control plunger (2) lifts off the lever (1, Figure 1).
|
Center/replace air flow sensor plate,
 2.1.
Replace air flow sensor. |
| 2.1 |
Control plunger |
|
Depress air flow sensor plate (4) by hand.
Release air flow sensor plate (4) slowly. |
Control plunger (2) should remain in contact with the lever (1).
|
Replace fuel distributor. |
| 3.0 |
Check control plunger
(2, Figure 1) in fuel distributor for leakage. |
|
Press air flow sensor plate (4) completely down and hold in this position (illuminate intake with borescope).
|
Slight seepage (drops) is permissible. |
Replace fuel distributor. |
| 4.0 |
Fuel pressures |
Connect pressure gauge. Connect hose "A" to lower chamber using adaptor (044), connect hose "B" to upper chamber, 31 , Figures 1 or 2.
When connecting pressure gauge, do not contact air flow sensor with wrench. |
|
|
|
| 4.1 |
System pressure |
|
Engine: at Idle
Valve on pressure gauge open. |
6.2 - 6.4 bar |
Check fuel pump,
Replace diaphragm pressure regulator,
Check fuel return line for restrictions.
|
| 4.2 |
Lower chamber pressure |
|
Engine: at Idle and at operating temperature.
Electrohydraulic actuator connector unplugged, valve on pressure gauge closed.
|
Approx. 0.4 bar below system pressure. |
Replace electrohydraulic
actuator (Y1) |
| 5.0 |
Deceleration shut-off
(Engine 104 only) |
Pressure gauge |
Engine: at Idle and at operating temperature.
Raise engine speed to 2500 rpm and then close throttle valve.
|
Lower chamber pressure must increase to system pressure until combustion resumes. |
Check deceleration shut-off, see 23 37.0. |
| 6.0 |
Acceleration enrichment |
Pressure gauge |
Ignition: OFF
ECT sensor (B11/2) unplugged. Using two resistance substitution units, simulate 2.5 k  resistance (+ 20°C) at sockets 2 and 4 as well as at sockets 1 and 3 ( 32 , Figures 2 and 3).
Engine: at Idle
Rev engine abruptly.
|
Approx. 0.5 bar below system pressure
Pressure in lower chamber must decrease to < 5.5 bar.
|
23 1.0 ,
23 10.0 ,
23 14.0. |
| 7.0 |
Fuel system leakage |
Pressure gauge |
Engine: OFF |
System pressure drops below opening pres-sure of injectors to approx.
3.5 bar.
|
If pressure drops immediately to
0 bar, replace check valve in fuel pump.
If pressure drops slowly below 3.5 bar, 7.1 - 7.4 |
| 7.1 |
Diaphragm pressure regulator |
|
Disconnect fuel return line at diaphragm pressure regulator. |
No fuel should flow out of diaphragm pressure regulator (slight seepage is permissible).
If fuel flows out of the fuel return line, plug line immediately.
|
Replace diaphragm pressure regulator. |
| 7.2 |
Fuel accumulator |
Pressure gauge |
.
Pinch leak-off line on fuel accumulator. |
Fuel pressure should no longer drop.
|
Replace fuel accumulator. |
| 7.3 |
Start valve |
|
|
|
33 or 34.
|
| 7.4 |
Fuel distributor |
|
Test steps 7.1 - 7.3 ok |
|
Replace fuel distributor.
|
| 7.5 |
External leakage |
|
Disconnect pressure gauge, wiping up any spilt fuel with a rag. Reconnect fuel lines.
Engine: at Idle |
All fuel connections must be tight (no leaks). |
|
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