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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1027 (Engine Controls - 6.6L (LLY) (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:  If there is fuel in the engine oil, fuel may be leaking from the fuel injector or fuel injection pump into the crankcase.
  3. 7:  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.
  4. 8:  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.
  5. 9:  In some cases, no compression, possibly with excessive fuel, in a single cylinder can cause a no start.
  6. 10:  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. 11:  The engine will not run without an actual fuel rail pressure more than 10 MPa (1,450 psi).
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, P0193, P0335, P0336, P0340, P0370, P0374, P0601, P0602, P0603, P0604, P0611, P0612, P0642, P0643, P0670, P0698, P0699, P1621, P1626, P1631, P1683, P1687, or U0105?		 - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3 Is the customer concern with a fuel smell or fuel leak? - Go to Fuel Leaks  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 15 
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 18 
6  Inspect for the following conditions:
Did you find and correct the condition?		 - Go to Step 26  Go to Step 7 
7 
  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 8  Go to Step 23 
8  Does the pressure measure more than the specified value for more than 2 minutes? 2 psi Go to Step 9  Go to Step 12 
9  Perform the Engine Compression Test. Refer to Engine Compression Test in Engine Mechanical. Repair the engine as necessary.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 10 
10  Did any of the cylinders emit any fuel vapor during the Engine Compression Test? - Go to Step 22  Go to Step 11 
11 
  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 13  Go to Step 12 
12
  1. Prime 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  Go to Fuel System Diagnosis - High Pressure Side 
13
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 26  Go to Step 14 
14 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 26  Go to Diagnostic Aids
15
  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 17  Go to Step 16 
16 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 26  Go to Step 21 
17 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 26  Go to Step 19 
18
  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 Wiring Repairs in Wiring Systems.
  2. Replace the fuse if necessary.
Did you find and correct the condition?		 - Go to Step 26  Go to Step 20 
19 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 26  Go to Step 24 
20
  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 26  Go to Step 21 
21 Test for an intermittent and for a poor connection at the ECM. 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 26  Go to Step 25 
22
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 (Left) or Fuel Injector Replacement (Right) .Did you complete the replacement?		 - Go to Step 26  -
23
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 26  -
24 Replace the FRP sensor. Refer to Fuel Rail Pressure (FRP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 26  -
25 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 26  -
26
  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 27  Go to Step 2 
27
  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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