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Home >> GMC >> 1993 >> C3500 HD 6.2 J, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Basic Testing >> A-3, No-Start Diagnosis >> No Start - Engine Cranks Okay (Except 3.8L With C(3)I) >> Fuel System (4.3L Turbo PFI)

Fuel System (4.3L Turbo PFI)

  1. Before checking fuel system for a no-start condition, check ignition for adequate spark. Check for proper fuel pump pressure and capacity. See A-7, BASIC FUEL SYSTEM CHECKS (GASOLINE).
  2. Disconnect injector harness. Turn ignition on, and check for battery voltage at each injector harness. Battery voltage should be present on one side of each injector. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both injector terminals, check for wires shorted together.
  3. If battery voltage is present on only one terminal, connect injector test light to injector harness. Crank engine, and note light. Repeat on other injector connectors. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article in this section.
  4. If light does not flash, disconnect distributor 4-wire HEI-EST connector. Momentarily touch test light from battery voltage to ECM RPM reference wire (circuit No. 430) of 4-wire connector. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire or injector drive (ground) circuit. If wiring is okay, replace faulty ECM.
Fig 1: HEI Ignition & Injector Circuits (2.5L)
G92H21755Courtesy of GENERAL MOTORS CORP.
Fig 2: HEI Ign. & Inj. Circ.(2.8L, 4.3L & V8 C,K & P Series W/ M/T)
G93E76418Courtesy of GENERAL MOTORS CORP.
Fig 3: HEI Ignition & Injector Circuits (3.1L)
G91G13603Courtesy of GENERAL MOTORS CORP.
Fig 4: HEI Ignition & Injector Circuits (4.3L Turbo)
G92J21757Courtesy of GENERAL MOTORS CORP.
Fig 5: HEI Ignition & Injector Circ. (4.3L S & T Series P/u W/ M/T)
G93F76419Courtesy of GENERAL MOTORS CORP.
Fig 6: HEI Ignition & Injector Circuits (4.3L S & T Series Utility With M/T & All Models With 4L60-E A/T - Except CPI)
G93I76420Courtesy of GENERAL MOTORS CORP.
Fig 7: HEI Ignition & Injector Circuits (4.3L With 4L60-E A/T & CPI)
G93J76421Courtesy of GENERAL MOTORS CORP.
Fig 8: HEI Ignition & Injector Circ. (All Engines W/4L80-E Trans.)
G91I13605Courtesy of GENERAL MOTORS CORP.
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