Maintenance Manual for Chery·Windcloud
Marelli EFI System
7. Electric Fuel Pump
Purpose: to carry fuel from fuel tank to
engine fuel injection system at a certain
pressure and flow rate (different in systems).
Composition and principle: electric fuel
pump is coaxially installed with pump motor
in the same casing. It is constituted by direct
current motor, vane pump and end cover
(integrating check valve, decompression
valve and anti-electromagnetism
interference component). Pump and motor in
the casing are surrounded by fuel, through
which they reject heat and get lubricated.
Accumulator supplies power to electric fuel
pump through fuel pump relay, which closes
pump circuit only when the engine is
starting or running. In case engine stops due
to failure, fuel pump stops automatically.
The maximum pressure of electric fuel
pump outlet is determined by decompression
valve between 450-650kPa, while the
pressure of entire fuel system is
350kPa in
general.
Flow rate of fuel pump is 76L/H.
Caution: Fuel temperature has fairly big
impact on fuel pump performance, in case of
longstanding operation under high
temperature condition, when fuel
temperature is higher than a certain value,
the pressure of fuel pump drops dramatically,
in this case, if engine fails to start when
warming-up vehicle, please check carefully
whether the high temperature performance
of fuel pump is out of condition.
Working temperature: -30 - +70°C
Electric fuel pump
Main power
Power relay
Fuel pump control
Circuit diagram of electric fuel pump
Fuel pump relay is controlled by ECU
15#pin.
Pins: electric fuel pump has 2 pins, which
connecting with fuel pump relay. “+” and
“-” are marked on the fuel pump housing
beside both of the 2 pins, which indicates
connecting with anode and cathode
respectively.
ECU 70# pin controls fuel pump relay.
Troubleshooting: generally the failure of
fuel pump appears as insufficient fuel
pressure or no pumping-out of fuel. In case
of troubleshooting, system fuel pressure
shall be checked to see if it is within the
scope of specified value and if pipeline is
leaking.
In addition,fuel tank’s positive pressure and
negative pressure will have impact on fuel
system and further on EFI performance.
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