Lack of Power, Sluggishness, or Sponginess. GMC Truck GMC K Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Pickup - 4WD 🢒 Engine 🢒 Engine Controls - 6.5L 🢒 Lack of Power, Sluggishness, or Sponginess

Checks

Action

Definition: The engine delivers less than expected power. There is little or no increase in speed when partially applying the accelerator pedal.

Preliminary Checks

•	Refer to Symptoms .

•	Compare the vehicle with a similar unit. Make sure the vehicle has an actual problem.

•	Remove the air filter and check for dirt, or for air ducts being plugged. Replace as necessary.

•	Check for a proper transmission shift pattern and down shift operation.

•	Check the fuel quality.

•	Check the engine oil level and quality.

Fuel System Checks

•	Check the fuel supply to the injection pump and the fuel return from the injection pump. Refer to Fuel Supply System Check .

•	Check the fuel pump operation.

•	Check for malfunctioning fuel injection nozzles.

•	Check the TDC Offset value. Refer to Fuel Injection Pump Top Dead Center Offset Adjustment .

Exhaust System Checks

•	Check the exhaust system for a possible restriction. Refer to Restricted Exhaust System Check .

•	Inspect the exhaust system for leaks.

Air Intake System Checks

•	Check for an air leak or restriction in the air inlet ducts or the intake manifold.

•	Check for a worn or damaged turbo charger turbine wheel, shaft or compressor wheel.

Engine Mechanical Check

Check the engine for the following:

•	Low compression

•	Improper valve timing

•	Improper or worn camshaft

Additional Checks

•	Check the control module grounds for being clean, tight, and in their proper location. Refer to Engine Controls Components .

•	Check the torque converter clutch (TCC) operation.

•	Check the A/C operation. Refer to Air Conditioning (A/C) Request Circuit Diagnosis .

•	Check the generator output voltage. Repair if less than 9 volts or more than 16 volts.