Benelli ZAFFERAN 250, Service Manual

Page: 185 / 187

185
f) Whether the clearance of crankshaft position sensor is too large
17.4.3.3 Fault Description- Startup Failure Accompanied with Backfire
a) Check whether the high-tension cable of ignition coil is loose
b) Whether the timing gear is loose.
17.4.3.4 Fault Description- Unstable Idle Speed
Idle speed
control system: Check whether the idle speed by-pass bolt is too loose or tight. Usually it is
necessary to screw 2 turns.
Oil supply system Whether there is an oil pipeline leak
17.4.3.5 Fault Description- Too High/Low Idle Speed
(Apparent Non-conformity to Target Idle Speed)
Idle speed

When the water temperature is lower than 68
℃
, the system will increase the idle
speed to is too high:
accelerate the warming up. Besides this normal process, check according to the
following
steps.

Check whether the idle air bypass hole is too large.

Check whether the air valve clearance, especially the exhaust valve clearance, is
too large.
Idle speed

Check the oil amount in the fuel tank, the fuel filter, the oil line pressure and the oil
is too low: nozzle.

Check whether the idle air bypass hole is too tiny.

Check whether the air valve clearance is too small.
17.4.3.6 Fault Description- Unstable Idle Speed Slowing Down with
Flameout
a)
Check the valve clearance
b) Check whether the idle air bypass hole and throttle body are too dirty
17.4.3.7 Fault Description-Poor Acceleration
a)
Whether the parameters at idle speed and high idle speed are normal
b) Check the oil amount in the fuel tank, and fuel filter.
c) Check whether the exhaust system is blocked, e.g., whether the ternary catalytic converter
is clogged because of burning engine oil or damages.
d)
Check the oil line pressure and the oil nozzle.
e)
Check whether the trouble light turns on and whether it is because only one cylinder can work
normally to ignite.