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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC P42 Commercial Chassis 🢒 Engine 🢒 Engine Controls - 6.5L (L57) 🢒 Cuts Out, Misses

Cuts Out, Misses EFI

Checks

Action

Definition: A steady or jerking that follows the engine speed, usually more pronounced as the engine load increases which is not normally felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound during idle, low speed, or hard acceleration due to the fuel starvation that can cause the engine to cut-out.

Preliminary Check

Refer to Symptoms .

Ignition System Checks

Check for a cylinder misfire.

Engine Mechanical Checks
    • Perform a cylinder compression check. Refer to Engine Mechanical.
    • Check the engine for the following:
       - Improper valve timing
       - Bent pushrods
       - Worn rocker arms
       - Worn camshaft lobes
       - Broken or weak valve springs
    • Check the intake and exhaust manifold passages for a casting flash. Refer to Engine Mechanical.

Fuel System Checks
    • Check the fuel system for a plugged fuel filter, low fuel pressure, etc. Refer to Fuel Supply System Check .
    • Check for water contamination in the fuel. Refer to Contamination Testing .

Cuts Out, Misses MFI

Checks

Action

Definition: A steady or jerking that follows the engine speed, usually more pronounced as the engine load increases which is not normally felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound during idle, low speed, or hard acceleration due to the fuel starvation that can cause the engine to cut-out.

Preliminary Check

Refer to Symptoms .

Ignition System Checks

Check for a cylinder misfire:

  1. Start the engine.
  2. Allow the engine to stabilize.
  3. Perform the injector balance test. Refer to Injection Nozzle(s) Diagnosis .
  4. If there is no RPM drop on one or more of the cylinders, or if there is an excessive variation in drop, refer to Engine Mechanical.

Engine Mechanical Checks
    • Perform a cylinder compression check. Refer to Engine Mechanical.
    • Check the engine for the following:
       - Improper valve timing
       - Bent pushrods
       - Worn rocker arms
       - Worn camshaft lobes
       - Broken or weak valve springs
    • Check the intake and exhaust manifold passages for a casting flash. Refer to Engine Mechanical.

Fuel System Checks
    • Check the fuel system for a plugged fuel filter, low fuel pressure, etc. Refer to Fuel Supply System Check .
    • Check for water contamination in the fuel. Refer to Contamination Testing .