S15/T15 Sonoma P/U 2WD V6-4.3L VIN W (1996)
Diagnostic Aids
An inoperative fuel pump relay can result in long cranking times. The time necessary for the oil pressure to reach the pressure required in order to close
the oil pressure switch and supply the necessary current for the fuel pump causes the extended crank period. If the fuel pump relay circuit checks out OK,
refer to Fuel System Pressure Test. See: Computers and Control Systems/Testing and Inspection/Component Tests and General Diagnostics/Fuel System
Pressure Test
Excessive fuel may also cause long cranking times which is accompanied by the following conditions:
1. A start that is not as fast as normal.
2. A puff of black smoke at the tailpipe. An improperly connected or faulty Evaporation Emission (EVAP) canister control valve can cause this
problem. Disconnect the EVAP purge hose from the EVAP canister control valve in order to diagnose.
One or more leaking poppet nozzles may also extend the cranking time. Perform the Poppet Nozzle Test, in the Injector Balance Test Table. Refer to
Fuel Injector Balance Test. See: Computers and Control Systems/Testing and Inspection/Component Tests and General Diagnostics/Fuel Injector
Balance Test Procedure
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step checks for the correct operation of the fuel pump.
3. This step checks the operation of the fuel pump by supplying 12 volts to the fuel pump control circuit.
5. This step checks the battery feed circuit to the fuel pump relay.
10. This step checks for the proper operation of the fuel pump relay.
