Engine Cranks But Does Not Run. GMC Truck GMC C-Series Medium Duty Truck B7 2002

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C-Series Medium Duty Truck B7 🢒 Engine 🢒 Engine Controls - 8.1L 🢒 Engine Cranks But Does Not Run

Description

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis.

The Engine Cranks but Does Not Run diagnostic table assumes the following:

•	The battery is completely charged. Refer to Battery Inspection/Test in Engine Electrical.

•	The cranking speed is within specifications. Refer to Engine Cranks Slowly in Engine Electrical.

•	There is adequate fuel in the fuel tank.

Diagnostic Aids

Inspect for the following conditions:

•

Mass air flow (MAF) is compared to a calculated mass air flow based upon the manifold absolute pressure (MAP), throttle position (TP), and engine RPM readings. A skewed or unresponsive MAP sensor at KEY ON will cause the predicted air flow value to be inaccurate. Compare MAP and TP sensor values to that of a known good vehicle.

•	Faulty engine coolant temperature (ECT) sensor. Using a scan tool, compare engine coolant temperature with intake air temperature (IAT) on a completely cool engine. The engine coolant temperature should be within 3°C (5°F) of the intake air temperature.

For an intermittent condition, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step determines if the ignition relay is providing the listed circuit breakers with voltage.

This step determines if the fuel pump is operating electrically.

Step

Action

Values

Yes

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Turn ON the ignition, with the engine OFF.
With a scan tool, observe the DTC information.

Does the scan tool display DTCs P0230, P0335, P0336, P0601, P0602, P0604, P0606, P1626, P1631, or P1683?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

Turn ON the ignition, with the engine OFF.
Probe both sides of the following circuit breakers with a test lamp connected to ground.

•

Odd INJ

•

Even INJ

Does the test lamp illuminate on both sides of the circuit breakers?

Go to Step 4

Go to Ignition Relay Diagnosis

Turn OFF the ignition.
Disconnect a spark plug wire.
Install the J 26792 spark tester to the spark plug wire.
Attempt to start the engine.

Does the spark tester spark?

Go to Step 5

Go to Electronic Ignition (EI) System Diagnosis

With a scan tool, command the fuel pump ON.

Does the fuel pump turn ON?

Go to Step 6

Go to Fuel Pump Electrical Circuit Diagnosis

Turn OFF the ignition.
Install the J 34730-1A fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
Turn ON the ignition, with the engine OFF.
With a scan tool, command the fuel pump ON.

Is the fuel pressure within the specified range while the fuel pump is operating?

384-425 kPa

(55-62 psi)

Go to Step 7

Go to Fuel System Diagnosis

Turn OFF the ignition.
Disconnect an injector connector.
Install the J 34730-405 injector test lamp to the injector connector.
Attempt to start the engine.

Does the test lamp blink while the engine is cranking?

Go to Step 8

Go to DTC P0200

Inspect for the following conditions:

•	Collapsed air intake duct

•	Restricted air filter element--Refer to Air Cleaner Element Replacement .

•	Spark plugs for being gas or coolant fouled--Refer to Spark Plug Inspection . If the spark plugs are fouled, determine what caused the condition.

•	Engine mechanical condition, such as worn timing chain and gears, low compression, etc.--Refer to Symptoms - Engine Mechanical in Engine Mechanical.