GM Service Manual Online
For 1990-2009 cars only

Hard Start Symptom

Step

Action

Value(s)

Yes

No

Definition: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately stalls.

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to the Powertrain OBD System Check

2

  1. Perform a bulletin search.
  2. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

--

Go to Step 20

Go to Step 3

3

Was visual/physical check performed?

--

Go to Step 4

Go to Visual /Physical Check.

4

Check Engine Coolant Temperature (ECT) sensor for being shifted in value. With the engine completely cool, compare Engine Coolant Temperature to Intake Air Temperature.

Are ECT and IAT within the specified value of each other?

±3°C (±5°F)

Go to Step 8

Go to Step 5

5

  1. Using a Scan Tool, display engine coolant temperature and note value.
  2. Check resistance of engine coolant temperature sensor.
  3. Refer to Engine Coolant Temperature Sensor Temperature vs. Resistance chart on DTC P0118 Diagnostic Support for resistance specifications.

Is resistance value near the resistance for the temperature noted?

--

Go to Step 7

Go to Step 6

6

Replace the ECT sensor.

Is action complete?

--

Go to Step 20

--

7

Locate and repair high resistance or poor connection in the ECT signal circuit or the ECT sensor ground.

Is Action complete?

--

Go to Step 20

--

8

  1. Check for faulty, plugged, or incorrectly installed Crankcase Ventilation valve.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 9

9

  1. Check for Water or alcohol contaminated fuel using J 39383-A. Refer to Engine Fuel.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 10

10

  1. Perform procedure in Fuel System Diagnosis.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 11

11

  1. Visually/Physically inspect secondary ignition wires. Check for the following conditions:
  2. • Check all Ignition wire resistances; should be less than the specified value.
    • Ignition wires for cross firing.

       Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.

    • Ignition wires arcing to ground.
    • Ignition wires for improper routing.
  3. If a problem is found, repair as necessary.

Was a problem found?

30 K ohms (30,000 ohms)

Go to Step 20

Go to Step 12

12

  1. Check for proper ignition coil output voltage with spark tester J 26792 (ST 125):
  2. • Clip the spark tester J 26792 to engine ground.
    • Connect J 26792 to an ignition wire then ground spark plug end of ignition wire from companion cylinder. The companion cylinder is the cylinder that shares the same ignition coil.
    • Crank the engine while observing the spark tester J 26792; a crisp blue spark should be observed.
    • Repeat the above steps for each coil.
  3. If adequate spark is not present at all coils, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 13

13

    Notice: Determine the cause of the oil or gas fouled spark plugs in order to avoid damage to the new spark plugs.

  1. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Refer to Electronic Ignition System.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 14

14

  1. Check for loose ignition control module ground. Refer to Electronic Ignition System.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 15

15

  1. Remove ignition coils and check the ignition coils for cracks or carbon tracking.
  2. If a problem is found, replace affected coil(s) as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 16

16

  1. Check ignition coil secondary resistance.
  2. Replace any coil(s) which are not within the specified values.

Did any coil(s) require replacement?

5K-7K ohms (5000-7000 ohms)

Go to Step 20

Go to Step 17

17

  1. Check IAC operation. Perform procedure in DTC P0506 diagnostic table.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 18

18

  1. Check for the following Engine Mechanical problems. Refer to Engine Mechanical:
  2. • Low compression,
    • Leaking cylinder head gaskets,
    • Worn or incorrect camshaft
  3. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 19

19

  1. Review all diagnostic procedures within this table.
  2. If all procedures have been completed and no malfunctions have been found, review/inspect the following:
  3. • Visual/physical inspection.
    • Scan Tool data.
    • Freeze Frame data/Failure Records Data.
    • All electrical connections within a suspected circuit and/or system.
  4. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Review Technical Service Bulletins

20

Operate the vehicle to duplicate conditions present when the original symptom was noted.

Is symptom still present?

--

Go to Step 3

Repair complete