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 On Board Diagnostic (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 Checks

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. Refer to Temperature vs Resistance .

Is resistance value near the resistance for the temperature noted?

--

Go to Step 7

Go to Step 6

6

Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement .

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. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

--

Go to Step 20

--

8

  1. Check for faulty, plugged, or incorrectly installed crankcase ventilation valve. Refer to Crankcase Ventilation System .
  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 contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Testing Procedure .
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

Go to Step 10

10

  1. Check Fuel System Pressure. Refer to Fuel System Pressure Test .
  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.
    • Ignition wires arcing to ground.
    • Ignition wires for improper routing.

    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. Refer to Electronic Ignition System On-Vehicle Service.

  3. If a problem is found, repair as necessary.

Was a problem found?

30K 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 :
  2.  - Clip the spark tester to engine ground.
     - Connect one end of a spark plug wire to the spark tester; connect the other end of the spark plug wire to the coil being tested.
     - Connect one end of another spark plug wire to the other coil tower; connect the other end of the spark plug wire to ground.
     - Crank the engine while observing the spark tester; 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

  1. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.

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

  1. 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.
  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. Refer to Ignition Control Module Replacement .

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. Refer to Ignition Control Module Replacement .

Did any coil(s) require replacement?

5-8K ohms (5000-8000 ohms)

Go to Step 20

Go to Step 17

17

  1. Check IAC operation. Refer to Idle Air Control (IAC) System Check .
  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

Refer to 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

System OK