Operation and Maintenance Manual forWP10 Series Four-valve Diesel Engine (China IV, V)
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(4) Crankshaft and camshaft signals lost
The diesel engine is provided with two speed sensors, which are mounted on the outsides of flywheel housing and
high pressure fuel pump respectively, and they serve as crankshaft position sensor and cylinder identification
sensor respectively. The fuel injection timing of electronic control engine depends onthese sensors. Both signals
will be lost when the diesel engine fails to start.
◆ Possible causes for loss of both signals
(1) The sensor is damaged, or the harness is short-circuited or open-circuited;
(2) The sensor is not fastened, causing too large or too small clearance (1±0.5mm in general) between the
sensor and the sensing tooth.
Troubleshooting: check the sensor and harness for damage and reliable connection.
◆ To ensure signal synchronization, the reassembly of high pressure fuel pump and flywheel must be
performed in strict accordance with related process documents.
6.2.2The engine is hard to start
Causes and troubleshooting:
◆ The diesel engine has not been running for a long time: Insert the fuel return pipe to below the fuel level.
◆ There is air in the low pressure fuel line: Remove the air.
◆ Too weak crankshaft speed and camshaft speed signals, and too long synchronization judgment time: Find
the causes and make adjustment.
◆ Too low ambient temperature and failure of pre-heating device: Check the heating flange wiring, or replace
the pre-heating device.
◆ Poor diesel fuel or oil quality: Replace as required.
◆ Starter or flywheel gear with teeth collision: Replace the starter motor and flywheel ring gear.
◆ Piston ring or cylinder liner worn or valve seal not tight: Replace piston ring, cylinder liner, or valve seat
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