Chery A21 2005, Service Manual, Page: 349 / 475

CHERY
·
A21 SERVICE MANUAL ENGINE EFI SYSTEM
26
joint) leave digital multimeter to ohm shift, two
meter pen connect to the pins of canister valve,
it is 26
±
4
Ω
when it is 20 .
℃
3.12 FUEL PRESSURE REGULATOR
1)Exterior drawing
2)Installation position: Fuel bracket assembly
3)Purpose : Adjust the pressure inside of fuel pipe,
keep the System pressure around 350Kpa.
4)Working principle : See chart 3- 23, one piece of
flexible film made up of rubber and fiber separate the
fuel pressure regulator into two compartments. The
upper compartment communicates to the air, and
there is spring inside. The lower compartment is full
of fuel entering from the fuel intake under the fuel
pressure regulator. The lower part of the film gets the
pressure from fuel and the upper part gets the pressure
from air and spring. The film can distort and drive
valve seat making the valve open and close, but the
distortion is smaller the acting force of the spring may
be seemed as not changed. So the opening and closing
of the valve is decided by the pressure difference of
the fuel pressure from lower compartment and the air
pressure from the upper compartment. If the valve is
closed at first, then the fuel pressure increased
causing the pressure difference between upper and
lower compartments increased. At last the film was
raised up by the fuel pressure and valve is opened.
The fuel return to fuel tank from oil return port of
pressure regulator, the fuel pressure decreased until
the valve is closed. If the engine changes its working
conditions now, the pressure difference of fuel system
and the air pressure is about the same.
5)Malfunction and diagnosis method
l
Malfunction: fuel pressure is too high or too low,
difficult to start.
l
Reason: long time using without maintenance
causing: 1, strainer jammed; 2, particle causes big
leaking; 3, man made mechanical damages.
l
Service notice: 1, prohibit to use high pressure air
blowing film element; 2, Forbid using strong
Chart 3-22 Fuel Pressure Regulator
Chart 3-23cutaway View of Fuel
Pressure Regulator
A
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