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HOMESERVICE MANUALSCHEVROLET1987HI-CUBE 6.2 J, 475/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEIGNITION SYSTEMIGNITION SYSTEM - HEI (CARBURETED MODELS)SYSTEM TESTINGENGINE WILL NOT START
1987 Chevrolet Hi-Cube 6.2 J, 475/M40

Engine Will Not Start

1987 Chevrolet Hi-Cube 6.2 J, 475/M40SECTION Engine Will Not Start
NOTE: If a tachometer is connected to the tachometer terminal, disconnect it before proceeding with the test.
  1. Check spark at plug using Test Plug (ST-125), while cranking engine. See Fig 1. If no spark occurs, check another wire. If a few erratic sparks occur, it is considered no spark. If spark occurs, check fuel system and spark plugs.
    Fig 1: Modifying Spark Plug for Testing
    G9008Courtesy of GENERAL MOTORS CORP.
  2. If no spark occurs, check voltage at ignition coil "B+" (battery) terminal while cranking engine. If reading is under 7 volts, repair primary wire circuit. If reading is 7 volts or more, check "TACH" terminal voltage with ignition on.
  3. If reading is less than one volt, replace ignition coil. If reading is from one to 10 volts, replace module and check for spark. If spark occurs, system is okay. If no spark occurs, replace ignition coil.
  4. If reading is more than 10 volts, check for spark at coil output terminal using Test Plug (ST-125) while cranking engine. See Fig 2. If spark occurs, check cap and rotor for damage.
    Fig 2: Testing for Spark at Coil Output Terminal
    G9009Courtesy of GENERAL MOTORS CORP.
  5. If no spark occurs, remove pick-up coil connector from module. Turn ignition on. With high input impedance voltmeter, observe voltage at "TACH" terminal while test light is momentarily connected to module "P" terminal (NOT OVER 5 SECONDS). See Fig 3.
  6. If no drop in voltage occurs, check module ground circuit and for open wires from coil to distributor. If okay, replace module. If voltage drop does occur, check for spark from coil with Test Plug (ST-125) as test light is removed from module "P" terminal.
  7. If spark occurs, replace pick-up coil. If no spark occurs, use a module tester and follow instructions. If module tester is not used, check ignition coil ground circuit.
  8. If okay, replace ignition coil and repeat check for spark from coil as outlined in step 6). If spark occurs, system is okay. If no spark occurs, install original coil and replace module.
Fig 3: Distributor Component Testing
G9010Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.