S10/T10 P/U 2WD V6-4.3L VIN W (1997)
Fuel Injector: Description and Operation
Fuel Injector And Poppet Nozzles
Each SFI fuel injector assembly is a solenoid-operated device, controlled by the VCM. The SFI fuel injector assembly meters the pressurized fuel
through a poppet nozzle to a single engine cylinder.
The VCM energizes the injector solenoid, which opens an armature valve (1), allowing fuel to flow past the ball valve and through a fuel tube to the
poppet nozzle.
An increase in fuel pressure causes the poppet nozzle ball to open from its seat (2) against the extension spring force. This allows the fuel to flow from
the nozzle (at approximately 280 kPa (40 psi)).
De-energizing the injector solenoid closes the armature. De-energizing also reduces the fuel pressure acting on the poppet nozzle ball. The extension
spring closes the ball to the seat. The extension spring also checks the pressure between the ball and seat and the injector armature and fuel tube shutoff.
An injector poppet nozzle that is stuck partly open would cause a loss of pressure after the engine shut down. Consequently, the driver would notice long
cranking times on some engines. Dieseling could also occur because the fuel injector could deliver some fuel to the engine after the driver turns the
ignition to OFF. These components are diagnosed in The Injector Balance Test and The Injector Coil Test. Refer to Fuel Injector Balance Test and
Fuel Injector Coil Test.
