Fuel Pump Speed Control Relay Function; Fuel Pump Speed Control Relay Operation; Fuel Pump Resistor Function - Mazda RX-8 2004 Service Highlights

FUEL PUMP SPEED CONTROL RELAY FUNCTION

• Supplies power to the fuel pump according to control signals from the PCM.
• For fuel pump speed control, refer to CONTROL SYSTEM, FUEL PUMP SPEED CONTROL. (See 01–40–23
FUEL PUMP CONTROL OUTLINE, 01–40–24 FUEL PUMP CONTROL BLOCK DIAGRAM, 01–40–24 FUEL
PUMP CONTROL OPERATION.)
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FUEL PUMP SPEED CONTROL RELAY OPERATION

• Reduces voltage by routing it through the fuel pump resistor to protect the fuel pump when required fuel
amount is low due to low engine speed.
FUEL PUMP SPEED CONTROL RELAY OFF
FUEL PUMP RELAY
FUEL PUMP SPEED
CONTROL RELAY
FUEL PUMP
RESISTOR
: CURRENT FLOW
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FUEL PUMP RESISTOR FUNCTION

• Supplies voltage to the fuel pump via the fuel pump resistor to protect the fuel pump when the injection amount
is low (when engine speed is low).
• A fuel pump resistor with a resistance of 0.304—0.336 ohms has been adopted.
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FUEL SYSTEM
MAIN FUSE BLOCK
FUEL PUMP SPEED
CONTROL RELAY
PCM
5P
4M
FUEL PUMP
B
FUEL PUMP RESISTER
FUEL PUMP SPEED CONTROL RELAY ON
FUEL PUMP RELAY
FUEL PUMP SPEED
CONTROL RELAY
FUEL PUMP
RESISTOR
CHU011413350S06
01–14
CHU0114W012
CHU011413350S07
PCM
5P
4M
FUEL PUMP
B
CHU0114S013
CHU011413350S08
CHU0114S007
01–14–9