Low Pressure Fuel Pump Control System; Evaporation Purge System - Suzuki DF200 Service Manual

3-26 ENGINE CONTROL SYSTEM

LOW PRESSURE FUEL PUMP CONTROL SYSTEM

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Fuel flowing through the pump is the pump coolant.
The fuel pump should never be run dry for long peri-
ods or it will become damaged.
The low pressure fuel pump is an electrically operated type that
supplies fuel from the fuel tank to the vapor separator.
The pump is controlled by the ECM and operates with at approx.
100% duty under any of the conditions below.
• Six (6) seconds after the ignition switch has been turned ON.
• Whenever the ECM receives a signal input from the CKP sen-
sor.

EVAPORATION PURGE SYSTEM

The evaporation purge system connects the vapor separator
and the air intake silencer case with a hose in which the purge
valve is installed. This system' function is to prevent hard start-
ing of the engine during hot soak periods by controlling the dis-
charge of vapors from the vapor separator into the air intake
case.
The ECM outputs a signal to the purge valve for opening/closing
on the basis of signals from IAT sensor, cylinder temp. sensor,
exhaust manifold temp. sensor and CKP sensor. (Normally, the
purge valve closes when the engine in shut off and opens after
the engine has been started.)
NOTE:
• The purge valve is driven by a duty cycle control signal from
the ECM.
During the engines "hot soak period", the valve opens at
approx. 2000 r/min. and a 40 – 50% duty control takes place.
Otherwise, the valve opens after the engine has started and a
30 – 50% duty control takes place.
• Evaporative emissions can occur when fuel heats up and
evaporates from the vapor separator. They are also released
from a hot engine when it is running and/or idling.
After the engine is turned off, engine heat rises slightly as the
cooling system water flow ceases, causing a small portion of
the fuel in the vapor separator to vaporize. This is generally
termed the "hot soak period." Vapors are also released during
engine operation as new fuel enters the vapor separator push-
ing air and fuel vapors out.
• See page 5-17 for the evaporation purge system check.
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2
1. Purge valve
2. Hose (Vapor separator to purge valve)
3. Hose (Purge valve to air intake case)
Low pressure
fuel pump
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