Yamaha F400A 2022 - Checking the Low-Pressure Fuel Pump; Checking the Feed Valve (Low-Pressure Fuel Pump); Checking the Relief Valve (Low-Pressure Fuel Pump)

6-7
Low-pressure fuel pump
Checking the low-pressure fuel pump
1. Check:
• Electrical performance of the low-pres-
sure-fuel pump
See “Checking the low-pressure fuel
pump and high-pressure fuel pump”
(5-29).
Checking the feed valve (low-
pressure fuel pump)
1. Check:
• Feed valve air flow
a. Connect the special service tool “1” to
the fuel inlet “a”.
b. Apply positive pressure and check that
air comes out of the opposite end of
the feed valve.
No air comes out → Replace.
2. Check:
• Feed valve holding pressure
a. Connect the special service tool “1” to
the fuel outlet “a”.
b. Apply the specified positive pressure.
Cannot be maintained for 15 seconds
or more → Replace.
Checking the relief valve (low-
pressure fuel pump)
1. Check:
• Relief valve opening pressure
Out of specification → Replace.
a. Connect the special service tool “1” to
the relief valve inlet “a”.
b. Apply the positive pressure, and check
that the relief valve opens at the speci-
fied pressure.
Vacuum/pressure pump gauge
set “1”
90890-06945
Pressure/vacuum tester “1”
YB-35956-B
Holding pressure (positive pres-
sure)
200.0 kPa (2.00 kgf/cm², 29.0
psi)
1
a
Vacuum/pressure pump gauge
set “1”
90890-06945
Pressure/vacuum tester “1”
YB-35956-B
Opening pressure (positive pres-
sure)
72.5-93.5 kPa (0.73-0.94 kgf/
cm², 10.5-13.6 psi)
Vacuum/pressure pump gauge
set “1”
90890-06945
Pressure/vacuum tester “1”
YB-35956-B
1a
1
a