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4C20 Gasoline Engine Repair Manual
(d) If a fault occurs and the fuel pressure sensor and circuit DTC appears, check the fuel pressure sensor harness
and connection. Inspect the fuel pressure sensor if damaged.
The injection pump is an important component of the high pressure fuel supply system as part of the engine
management system. It is used to create high pressure in the fuel rail.
In the engine management system, the action of the high pressure fuel pump is monitored and controlled
directly by the engine control unit. The software in the engine control unit calculates the required mass of fuel
delivered by the pump according to the pressure to be set in the fuel system. The resulting value is converted into
the amount of fuel supplied, and the bypass valve response time is calculated, which ensures the timely supply of
the required amount of fuel to the fuel rail. The injection pump is a single-plunger pump that supplies fuel to the
fuel rail. The plunger of this pump is driven by the crankshaft using a pusher. In addition, the amount of fuel
supplied is controlled by an electrical signal from the engine control unit. At the inlet, the high pressure fuel pump
is connected to the low pressure fuel pipe. Fuel from the fuel tank through the fuel priming and low-pressure fuel
pipe enters the high-pressure fuel pump filter.
assembly and operation, which may result in fuel leakage.
(e) If a fuel injector or injector circuit DTC occurs in any of the cylinders, check the appropriate cylinder injector circuit
for proper static resistance.
(b) Check whether the injector O-ring is damaged or scratched due to incorrect assembly
and operation, which may result in air and oil leakage.
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3. Fault detection
HPFP
1. Purpose
(c) Check that the spray holes are not damaged or clogged. Components connecting the low pressure fuel lines to
the high pressure fuel system must be free of internal contaminants and particles larger than 200 µm. The external
connections of these components must be protected with dust-tight covers.
The injection pump has a bypass valve for precise control of fuel consumption. As the plunger moves inside
the pump, the fuel pressure rises. If the pressure in the fuel rail is lower than the pressure created by the injection
pump, the fuel from the pump through the high pressure fuel line is supplied to the rail. If the pressure in the fuel
rail is higher than the maximum set pressure, the fuel returns to the pump through the bypass valve. This is
necessary to relieve pressure in order to protect the fuel rail. The bypass valve with solenoid coil is activated when
a peak/"protective" current is applied. Two terminals of the e/m coil are connected to the injection pump, which is
directly connected to the engine control unit and the onboard network via the engine wiring harness. Control
signals from the engine control unit through the e / m coil are fed to the high pressure fuel pump to control the
bypass valve of the pump. Under the influence of the electromagnetic force created when current is applied to the
injection pump, the bypass valve closes to ensure that the specified fuel pressure is maintained. When power is
disconnected from the high pressure fuel pump e / m, the power on the coil automatically disappears, after which
the bypass valve opens under the influence of a return spring and fuel passes through it.
(a) Check if the fuel rail is subjected to permanent deformation due to incorrect
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