STEYR MOTORS Marine Engine 2012 Series, Service Manual

Page: 201 / 274

Fuel System
49/51 Z001138-1_2013-02-01
03.14.03 Disengagement methode of injection
NOTE:
Disengagement method of injection is a
simple and effective method to detect defective
unit injectors with regard to formation of air
bubbles in both the fuel system and the engine
cooling system or lack of power if related to
deficiencies in injection equipment.
NOTE: In case of air in the cooling
circuit/system use tool VR00147/0 to detect
CO2 concentration in coolant.
Preparation: Disconnect crankshaft, refer to
01.00.01 (item 2 - 3 remove valve cover).
1. Mount special tool No. VR00133/3 to
disconnect injection.
2. Start the engine, let it run in idle and check
if air bubbles form at the fuel return line.
NOTE: If there are no bubbles at idle speed of
engine, continue with item 3. Otherwise
investigate fuel suction line and fittings and
correct failure.
3. Bring engine to operating temperature and then test the vehicle under operating
conditions and watch for bubbles to form. Keeping this operating condition,
continue with item 4.
4. Loosen nut on cover (see ill.), screw in, with fast turns, screw (ill.1/pos.2) until
knocking noise disappears. Tighten nut (ill.1/pos.1) again. As a result, unit injector
is pressed down to such an extent that injector cam can no more touch the rocker
arm, thus preventing the injection of fuel. (respectively eliminating combustion)
5. Test the vehicle with disengaged unit injector under operating conditions and
6. Continue to check all other injectors (cylinders) one by one, in order to detect the
defective(s) unit injector(s).
NOTE: Air bubble formation will change and/or stop as soon as injection of defective
unit injector(s) is disengaged.
7. Replace defective unit injector(s). (Replace unit injector, refer to 03.02.02)