Backfire
Checks
| Actions
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DEFINITION:
Fuel ignites in the intake manifold, or in the exhaust system, making loud
popping noise.
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Preliminary Checks
|
| • | Search for service bulletins. |
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Fuel System
|
| • | Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis
. |
| • | Ensure each fuel injector harness is connected to the correct
injector/cylinder. Refer to
Engine Controls Schematics
Fuel Controls. |
|
Ignition System
|
| • | Check for proper ignition voltage output with the J 36012-A
spark plug jumper wires and J 26792
spark tester or equivalent. |
| • | Check the spark plugs for the following conditions: |
| - | Check for wet or fuel fouled spark plugs. |
| - | Check for cracks on the spark plugs. |
| - | Check for improper spark plug gap. |
| - | Check for burned electrodes or heavy deposits. |
| • | If the spark plugs are fuel or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
| • | Check the Ignition Control Module (ICM) for proper ground connection. |
| • | Check the ignition coils for cracks or carbon tracking. |
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Engine Mechanical
|
| - | Sticking or leaking valves. |
| - | Worn camshaft(s) lobe(s). |
| - | Excessive oil in combustion chamber-Leaking valve seals. |
| - | Low cylinder compression. |
| • | For incorrect basic engine parts. Inspect the following: |
| • | Refer to Engine Mechanical. |
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Additional Checks
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| • | Check Intake and exhaust manifold(s) for casting flash. Refer
to Engine Mechanical . |
| • | Check the exhaust system for possible restriction. Check the following: |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
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