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 dies.

1

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

--

Go to Step 2

Go to 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 19

Go to Step 3

3

Check to see if the driver is using the correct starting procedure as described in the owners manual. Educate the driver if they do not know.

Does the driver know the correct starting procedure?

--

Go to Step 4

Go to Step 19

4

Perform the careful visual/physical checks as described at the start of Symptoms section.

Is the action complete?

--

Go to Step 5

Go to Important Preliminary Checks

5

  1. Check the Engine Coolant Temperature (ECT) sensor for being shifted in value.
  2. With the engine completely cool, compare the engine coolant temperature to the intake air temperature.

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

± 3°C (± 5°F)

Go to Step 9

Go to Step 6

6

  1. Using a Scan Tool, display the engine coolant temperature and note the value.
  2. Check the resistance of the engine coolant temperature sensor. Refer to DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage for Diagnostic Support for the resistance specifications in the Temperature vs. Resistance Table.

Is the resistance value near the resistance for the temperature indicated?

--

Go to Step 8

Go to Step 7

7

Replace the ECT sensor.

Is the action complete?

--

Go to Step 19

--

8

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

Is the action complete?

--

Go to Step 19

--

9

  1. Check for proper operation of the MAP sensor.
  2. Repair if found malfunctioning, refer to Manifold Absolute Pressure Sensor Output Diagnosis .

Was a problem found?

--

Go to Step 19

Go to Step 10

10

  1. Check for proper operation of the TP sensor.
  2. Repair if found malfunctioning.

Was a problem found?

--

Go to Step 19

Go to Step 11

11

  1. Check for water or alcohol contaminated fuel using J  39383-A.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 19

Go to Step 12

12

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

Was a problem found?

--

Go to Step 19

Go to Step 13

13

  1. Check for proper ignition voltage output with spark plug jumper wires J 36012 and spark tester J 26792.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 19

Go to Step 14

14

    Notice: If spark plugs are gas or oil fouled, determime the cause of the fouling before replacing the spark plugs in order to avoid damage to the new spark plugs.

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

Was a problem found?

--

Go to Step 19

Go to Step 15

15

  1. Check for loose ignition control module ground.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 19

Go to Step 16

16

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

Was a problem found?

--

Go to Step 19

Go to Step 17

17

Check for the following Engine Mechanical problems:

    • Low compression.
    • Leaking cylinder head gaskets.
    • Worn or incorrect camshaft.

Was a problem found?

--

Go to Step 19

Go to Step 18

18

  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 items:
  3. • Visual/physical inspection.
    • Scan tool data.
    • All electrical connections within a suspected circuit and/or system.
  4. If a problem is found, repair as necessary.

Is action complete?

--

Go to Step 19

--

19

Operate vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

--

System OK

Go to Step 2