Yanmar 4JH4E - Fuel Feed Pump Inspection

6. Fuel Injection equipment
226
6.2.4 Fuel feed pump inspection
(1) Place the fuel feed pump in kerosene,
cover the discharge port with your finger,
move the priming lever and check for air
bubbles (Repair or replace any part
which emits air bubbles).
(2) Attach a vinyl house to the fuel feed
pump intake, keep the pump at the
specified depth from the fuel oil surface,
move the priming lever by hand and
check for sudden spurts of fuel oil from
the discharge port. If oil is not spurted
out, inspect the diaphragm and
diaphragm spring and repair/replace as
necessary.
(3) Diaphragm inspection
Parts of the diaphragm that are repeatedly
burned will become thinner or deteriorate over
a long period of time.
Check the diaphragm and replace if
necessary.
(4) Valve contact/mounting
Clean the valve seat and valve with air to
remove any foreign matter.
(5) Inspect the diaphragm spring and piston
spring for settling and the piston for
wear, and replace as necessary.
Note: Replace parts as an assembly.
Measuring cylinder
Tappet
Blocked
Air pressure kg/cm
3
Container filled
with light oil
010341-00E
Diaphragm
010342-00E
Inlet valve
Outlet valve
010343-00E