Yamaha F400A 2022 - Checking the Low-Pressure Fuel Pump Relay; Checking the High-Pressure Fuel Pump Relay

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Fuel control unit and component
d. Connect the direct injection pump cou-
plers.
Checking the low-pressure fuel pump
relay
1. Check:
• Low-pressure fuel pump relay
a. Disconnect the low-pressure fuel
pump relay coupler “a”.
b. Turn the main switch or power switch
to ON, and then measure the low-pres-
sure fuel pump relay input voltage.
c. Turn the main switch or power switch
to OFF.
d. Remove the low-pressure fuel pump
relay.
e. Connect the positive battery lead to the
terminal “b” and the negative battery
lead to the terminal “c”, and then check
for continuity between the terminals
“d” and “e”.
If there is no continuity → Replace.
Do not reverse the battery leads.
Checking the high-pressure fuel
pump relay
The high-pressure fuel pump relay cannot be
removed for testing or replaced as a single unit
because it is a component part of the electrical
management box.
1. Check:
• High pressure fuel pump relay
a. Connect the YDIS to display “VST fuel
pump relay”.
b. Turn the main switch or power switch
to ON, and then check that “ON” is dis-
played for “VST fuel pump relay” on the
YDIS screen.
c. Remove the fuse cover.
d. Measure the input voltage between the
high-pressure fuel pump fuse “a” and
ground.
Direct injection pump
Resistance (reference data)
0.45-0.55 Ω
Input voltage
12 V
Yellow/Red (Y/R)–Ground
a
a
Y/R
Battery lead
Terminal
de
Connect
Disconnect
b
c
d
e
a