Stop Solenoid - Yanmar 3TNV82A Service Manual

FUEL SYSTEM
Figure 7-1
The following describes the features of the MP fuel
injection pump, manufactured by Yanmar.
The fuel injection pump is a very important
component of the engine. It is capable of making
very precise fuel delivery adjustments according to
the varied loads applied to the engine.
All of the fuel injection pump components are very
precisely machined. It is extremely important to
follow good service practices and maintain
cleanliness when servicing the fuel injection pump.
The Yanmar MP "Mono-Plunger" Fuel Injection
Pump is a distributor type pump which consists of a
single fuel supply plunger, a distributor shaft, a
hydraulic head and a pump housing. The hydraulic
head has a delivery valve for each cylinder. The
fuel injection pump housing contains a governor
and an internal camshaft.
The fuel is pressurized by the up and down motion
of the camshaft-driven single plunger. It is then
distributed to the proper fuel injector by the rotating
distributor shaft.
There are two versions and sizes of the MP Fuel
Injection Pump. The smaller of the two pumps, the
MP2 pump, is used on the 3TNV82A - 4TNV88
model engines. The larger pump, the MP4 pump,
which has a larger single plunger and a more
aggressive cam profile, is used on the
4TNV94L - 4TNV106T model engines.
7-6

Stop Solenoid

The MP fuel injection pumps are equipped with a
stop solenoid that controls the fuel flow inside the
fuel injection pump.
With the starter switch in the OFF position, no
current flows to the stop solenoid and the solenoid
plunger is extended holding the fuel injection pump
fuel rack in the "closed" position and not allowing
fuel to flow through the injection pump and to the
engine.
0000038
When the starter switch is turned to the start
position, the "pull coil" (36.5 Amp draw / white wire)
inside the solenoid is activated and pulls the
solenoid plunger into the solenoid. This releases
the fuel injection pump fuel rack, allowing fuel to
flow through the injection pump and allowing the
engine to start and run.
When the starter switch is returned to the ON or
RUN position, the "pull coil" no longer receives
current and the "hold coil" (0.5 Amp draw / red wire)
inside the solenoid is activated. The "hold coil"
holds the solenoid plunger in the RUN position,
allowing fuel to continue flowing and he engine to
continue running.
To stop the engine, the key switch is turned to the
OFF position. Current no longer flows to the stop
solenoid "hold coil", and the solenoid plunger
extends and moves the injection pump fuel rack to
the "closed" position, shutting off the fuel flow and
stopping the engine.
Failure of the stop solenoid could result in the
engine not starting, the engine stopping suddenly,
the engine not continuing to run with the key switch
returned to the ON or RUN position, or the engine
failing to stop when the key switch is turned to the
OFF position. Use a multimeter or continuity light to
check for 12V at the stop solenoid connector in the
correct sequence.
TNV DI Service Manual
Introduction