Cub Cadet Yanmar 3TNV72 - Manual (Page 187)

FUEL SYSTEM
7-26 TNV IDI Service Manual
Fuel Injectors
Fuel Injector Test Results
Note: If the fuel injector fails any tests, it should be serviced or replaced as necessary. If the pressure is
outside specified limits, adjust the pressure. See Adjusting Fuel Injector Pressure on page 7-28.
A B C D E
Injection Pattern
Pressure Gauge
Reading
Gauge needle
fluctuates around
the valve opening
pressure.
Gauge needle
fluctuates around
the valve opening
pressure.
Gauge needle
stays at a position
near the valve
opening pressure.
Although the
gauge needle
reaches the valve
opening pressure,
the pressure drop
is large.
Pressure does not
increase even
when the tester
lever is operated.
Atomization
Pattern
5°-10° cone and
roughly uniform.
Atomization is
excessively
one-sided.
Although atomized
(burner like
shape), the needle
does not pulsate.
Bar shape with
excessive after
drops.
Drops.
Possible Cause
(Normal, injector is
good)
Normally caused
by carbon
contamination of
the nozzle tip.
Sometimes caused
by flaws in or
damage to the
needle tip.
Caused by
excessive carbon
contamination of
the nozzle tip.
Sometimes caused
by internal
contamination.
Damage to the
seat.
Contamination of
seat by fine foreign
particles.
Excessively worn
seat.
Sticking of needle.
Excessively
damaged or worn
seat.
Contamination of
seat by foreign
matter.
Damaged or
broken internal
parts or nozzle
case nut.
0001742
0001743 0001744
0001747
0
120
0001748
0
120
0001749
0
120
0001750
0
120
0001751
0
120
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