Yamaha F400A 2022 - Checking the Feed Valve (High-Pressure Fuel Pump)

6-15
Fuel hose, feed valve, relief valve, and fuel strainer
b. Apply the specified positive pressure
for 15 seconds or more.
2. Check:
• Relief valve opening pressure
Out of specification → Replace.
a. Connect a pressure pump “1” to the
fuel inlet “a”.
b. Block the fuel outlet “b” using a rubber
plug “2”.
c. Apply the specified positive pressure,
and check that the relief valve opens at
the specified pressure.
Checking the feed valve (high-
pressure fuel pump)
1. Check:
• Feed valve holding pressure
Out of specification → Replace.
a. Connect a pressure pump “1” to the
fuel outlet “a”.
b. Apply the specified positive pressure
for 15 seconds or more.
2. Check:
• Feed valve opening pressure
Out of specification → Replace.
a. Connect a pressure pump “1” to the
fuel inlet “a”.
b. Apply the specified positive pressure
and check that the feed valve opens at
the specified pressure.
Pressure pump “1”
(commercially available)
Opening pressure (positive pres-
sure)
445.0-455.0 kPa (4.45-4.55 kgf/
cm², 64.5-66.0 psi)
Pressure pump “1”
(commercially available)
1
a
1
b
a
2
Holding pressure (positive pres-
sure)
490.0 kPa (4.90 kgf/cm², 71.1
psi)
Pressure pump “1”
(commercially available)
Opening pressure (positive pres-
sure)
9.3-12.6 kPa (0.09-0.13 kgf/
cm², 1.3-1.8 psi)
1
a
1
a