Hyundai Sonata 1991 Shop Manual page 249

MPI SYSTEM
Power Supply And Fuel Pump Control
Y31DI3A
To injector
f_-~Purge
control sol. valve
To fuel
pumpl--~EGR
sol. valve (only california)
ECU
Ground
7
S2 Power
-o-Lc:'3'--------;>-~)-+----...-~-+-L-f-T--\
supply
Fusible link
Battery
til
To AFS
31YQ14
o While cranking (ignition switch at 5T), current flows through coil L, to close switch 5,. As a result, the fuel
pump is driven.
Current als,? flows through coil L
3
to close switch 5,. As a result, power is supplied to the ECU, AF5, igniter
and injectors.
o While the engine is running, the ECU turns on the power transistor to supply current to coil L, and to close
switch 5,. As a result, the fuel pump is driven.
o In the event of engine stall or other abnormal conditions, the ECU turns off the power transistor and open
the coil L, circuit. As a result. switch 5, opens to stop driving of the fuel pump, thus securing safety.
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