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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1026 (Engine Controls - 6.6L (Lb7) (Troubleshooting & Diagnosis) >> Troubleshooting >> Engine Cranks but Does Not Run >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 5:  This step tests for an ignition 1 voltage supply to the engine control module (ECM).
  2. 6:  This step tests the 12-volt reference circuit to the CKP sensor and the CMP sensor. The 12-volt reference circuit for the CKP sensor and the CMP sensor is connected internally within the ECM. If the 12-volt reference circuit is shorted to ground, the engine will not start and no engine speed will be indicated on the scan tool.
  3. 8:  If there is fuel in the engine oil, fuel may be leaking from the fuel injector or fuel injection pump into the crankcase.
  4. 9:  If the fuel system will not even briefly prime to 10 psi and will not start, the check valve in the fuel filter/heater element housing is stuck open.
  5. 10:  This step determines if the fuel system is bleeding down causing a no start. The fuel pressure will slowly drop to 0 psi, but should still be above 8 psi 10 seconds after pressurizing the fuel system.
  6. 12:  This step determines if the problem is a stuck open or broken fuel injector. If fuel vapors come out of any of the glow plug holes, excessive fuel is being sent into a cylinder, and not being distributed to all of the fuel injectors.
  7. 13:  The engine will not run without an actual fuel rail pressure more than 10 MPa (1,450 psi).
  8. 15:  If the no-start condition takes place in cold operating temperatures, 2-4° C (35-40° F) or colder, a glow plug system failure may cause the no-start condition.
  9. 17:  In some cases, no compression, possibly with excessive fuel, in a single cylinder can cause a no start.
Engine Cranks but Does Not Run

Step Action Values Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Turn On the ignition, with the engine OFF.
  2. Observe the DTC Information with a scan tool.
Does the scan tool display DTC P0090, P0335, P0336, P0340, P0370, P0374, P0380, P0601, P0602, P0603, P0604, P0611, P0612, P1621, P1626, P1631, P1683, or U1800?		 - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3 Is the customer's concern with a fuel smell or fuel leak? - Go to Fuel Leaks (Outside of Engine)  or Fuel Leaks (Inside of Engine)  Go to Step 4 
4 Observe the Actual Fuel Rail Pressure parameter with a scan tool.
Is the pressure within the specified range?		 1-1.8 MPa Go to Step 5  Go to Step 18 
5  Observe the Ignition 1 signal parameter with a scan tool.
Is the Ignition 1 signal parameter at the specified value?		 B+ Go to Step 6  Go to Step 24 
6 
  1. Attempt to start the engine.
  2. Observe the Engine Speed parameter with a scan tool while the engine is cranking.
Is the Engine Speed parameter more than the specified value?		 0 RPM Go to Step 7  Go to Step 19 
7
IMPORTANT: If there is high resistance in the signal or low reference circuits of the crankshaft position (CKP) sensor the Engine Speed parameter of the scan tool will display a value more than 0. It will not be an accurate measure of engine speed, and can cause an Engine Cranks but does Not Run condition.
Test the CKP sensor signal and low reference circuits for high resistance. Refer to Circuit Testing in Wiring Systems.Did you find and correct the condition?		 - Go to Step 34  Go to Step 8 
8  Inspect for the following conditions:
Did you find and correct the condition?		 - Go to Step 34  Go to Step 9 
9 
  1. Install the J 44638  Vacuum Gage to the fuel system service port on the right front side of the engine.
  2. Attempt to hand prime the fuel manager 30 times or until the specified pressure is reached.
Can you prime the system to the specified value?		 8 psi Go to Step 10  Go to Step 31 
10  Does the pressure measure more than the specified value for more than 2 minutes? 2 psi Go to Step 11  Go to Step 14 
11 Perform the Engine Compression Test. Refer to Engine Compression Test in Engine Mechanical - 6.6L. Repair the engine as necessary.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 12 
12  Did any of the cylinders emit any fuel vapor during the Engine Compression Test? - Go to Step 28  Go to Step 13 
13 
  1. Crank the engine for 15 seconds.
  2. Observe the Actual Fuel Rail Pressure parameter with a scan tool.
Is the Actual Fuel Rail Pressure parameter more than the specified value?		 10 MPa (1,450 psi) Go to Step 15  Go to Step 14 
14
  1. Reprime the fuel manager to 10 psi.
  2. Attempt to start the engine while the prime is still above 8 psi.
Does the engine start?		 - Go to Fuel System Diagnosis (Pickup)  or Fuel System Diagnosis (Cab Chassis)  Go to Fuel System Diagnosis - High Pressure Side 
15  Observe the Glow Plug System Type parameter with a scan tool.
Is the Glow Plug System Type Federal?		 - Go to Step 16  Go to Step 17 
16
IMPORTANT: Repeat this procedure on both banks of the engine. This test may be repeated as many times as necessary.
  1. Turn OFF the ignition.
  2. Connect a test lamp to a glow plug harness connector on one side of the engine.
  3. Turn ON the ignition, with the engine OFF.
Does the test lamp turn ON and OFF?		 - Go to Step 17  Go to Glow Plug System Diagnosis 
17  Inspect for the following conditions:
  • A plugged air filter
  • A collapsed air intake duct
  • The fuel heater is inoperative. If the customer concern is that the engine will not start when ambient temperatures are less than 2-4° C (35-40° F), refer to Fuel Heater Inoperative .
  • A restricted exhaust system-Refer to Symptoms - Engine Exhaust in Engine Exhaust.

Did you find and correct the condition?		 - Go to Step 34  Go to Diagnostic Aids
18
  1. Disconnect the fuel rail pressure (FRP) sensor.
  2. Observe the Actual Fuel Rail Pressure parameter on the scan tool.
Does the Actual Fuel Rail Pressure parameter measure more than the specified value?		 175 MPa Go to Step 23  Go to Step 22 
19
  1. Turn OFF the ignition.
  2. Disconnect the CKP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the 12-volt reference circuit of the CKP sensor with a DMM connected to a good ground.
Is the voltage more than the specified value?		 10 V Go to Step 29  Go to Step 20 
20
  1. Turn OFF the ignition.
  2. Disconnect the camshaft position (CMP) sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the 12-volt reference circuit of the CMP sensor with a DMM connected to a good ground.
Is the voltage more than the specified value?		 10 V Go to Step 30  Go to Step 21 
21 Test the 12-volt reference circuit of the CKP sensor and the CMP sensor for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 33 
22 Test the FRP sensor signal circuit for a short to ground. Refer to Circuit Testing in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 33 
23 Test the FRP sensor circuits for high resistance. Refer to Circuit Testing in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 25 
24
  1. Test the ignition 1 voltage circuit of the engine control module (ECM) for a short to ground, a high resistance, or an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
  2. Replace the fuse if necessary.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 26 
25 Test for an intermittent or for a poor connection at the FRP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 32 
26
  1. Clean and tighten the ECM shared ground. Refer to Power and Grounding Component Views in Wiring Systems.
  2. Attempt to start the engine.
Does the engine start?		 - Go to Step 34  Go to Step 27 
27 Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 34  Go to Step 33 
28
IMPORTANT: When the fuel injector pressure lines are removed, debris will fall on the fuel injector inlet fitting. Vacuum the debris from the area to prevent the debris from falling in the fuel injector.
Replace the fuel injectors on the affected cylinders. Refer to Fuel Injector Replacement .Did you complete the replacement?		 - Go to Step 34  -
29 Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 34  -
30 Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 34  -
31
IMPORTANT: Before replacing the fuel filter/heater element housing, inspect the fuel vent screw for damage or cross threading. Replace the vent screw w/"O" ring if either condition is found.
Replace the fuel filter/heater element housing. Refer to Fuel Filter/Heater Element Housing Replacement .Did you complete the replacement?		 - Go to Step 34  -
32 Replace the FRP sensor. Refer to Fuel Rail Pressure (FRP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 34  -
33 Replace the engine control module (ECM). Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 34  -
34
  1. Clear any DTCs with a scan tool.
  2. Attempt to start the engine.
Does the engine start and continue to run?		 - Go to Step 35  Go to Step 2 
35
  1. Allow the engine to idle until normal operating temperature is reached.
  2. Observe the DTC Information with a scan tool.
Are any DTCs displayed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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