Yanmar 4BY, Service Manual, Page: 155 / 275

FUEL SYSTEM
6-26
BY Service Manual
Repair
Replacing the Fuel Filter / Water Separator
1. Disconnect the battery negative (-) cable.
2. Close the fuel supply valve.
Figure 6-35
3. Loosen the drain plug (Figure 6-35, (3)) on the
bottom of the fuel filter / water separator and
drain off any water or dirt.
4. Disconnect water sensor connector
(Figure 6-35, (1)) .
5. Turn the filter bowl (Figure 6-35, (2))
counterclockwise to remove.
Figure 6-36
6. Remove the old filter element
(Figure 6-36, (3)) .
7. Clean the filter bowl. Inspect the water sensor
probe (Figure 6-36, (1)) for damage. Inspect
the bowl seal (Figure 6-36, (2)) .
IMPORTANT
When replacing fuel filters, always pre-fill
them with fresh, clean fuel to improve the
system ability to be bled.
8. Lubricate the seal at the top of the new filter
element and install (Figure 6-36, (3)) .
9. Lubricate the filter bowl seal and install the filter
bowl. Turn clockwise by hand to tighten.
10. Ensure drain plug (Figure 6-36, (4)) is securely
tightened.
11. Connect water sensor.
12. Open the fuel supply valve.
13. Connect the battery negative (-) cable.
14. Bleed fuel system and check for leaks. See
Bleeding the Fuel System on page 6-29.
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