Yanmar 3JH4E, Service Manual

Page: 90 / 350

2. Inspection and adjustment
70
[4JH4-TE and 4JH4-HTE]
When water and dirt are mixed in with the fuel, it
becomes impossible for the fuel injection pump
and the fuel injection valve to work. Drain
periodically to keep the filter from becoming
clogged. If no water or fuel drains from the fuel /
water separator, loosen the air bleeding bolt on the
fuel / water separator 2 - 3 times. This occurs
when the fuel level in the fuel tank is lower than the
position of the fuel / water separator.
1) Make sure the fuel cock of the fuel tank is
closed.
2) Loosen the hose clamp and remove the fire-
resistant cover, which is installed to the lower
part of the fuel filter / water separator to
protect the water alarm switch.
3) Attach a drain tube to the drain plug.
4) Loosen the drain plug at the bottom of the fuel
filter / water separator counterclockwise and
drain off any water or dirt.
Note:
If there is a large quantity of water and
sediment in the fuel / water separator, also
drain the fuel tank.
5) Tighten the drain plug.
6) Remove the drain tube.
7) Install the fire-resistant cover and tighten the
hose clamp.
8) Bleed air from the fuel system.
When there is a heavy deposit, drain the fuel
tank at the same time.
Fuel system air bleeding procedures
1) Check the fuel level in the fuel tank.
Replenish if Insufficient.
2) Open the fuel cock of the fuel tank.
3) Loosen the air bleeding bolt on the top of the
fuel filter by turning it 2-3 times with a minus
driver.
4) Feed the fuel with the priming pump. The
priming pump is on the top of the fuel filter.
Move the priming pump knob up and down
until fuel mixed with air bubbles flows out of
the air bleeding bolt.
5) Allow the fuel containing air bubbles to flow.
When the fuel coming out is clear and not
mixed with any bubbles, tighten the air
bleeding bolt.
In subsequent engine operation after the start-
up, the automatic air-bleeding device works to
purge the air in the fuel system. No manual air-
bleeding is required for normal engine operation.
Fuel filter
Loosen
Tighten
Drain plug
Air bleeding bolt
Drain tube
008421-01E
Priming pump
Air bleeding bolt
From fuel tank
To fuel injection pump
008415-01E