* With a Duramax Diesel Engine (LB7, LLY, or LBZ): The fuel filter is typically located on the frame rail, near the driver's side, toward the rear of the engine compartment. It's often a large, cylindrical canister.
* With a Gasoline Engine (e.g., Vortec 6.0L or 8.1L): On gasoline engines, the fuel filter is usually *inside* the fuel tank, meaning it's not accessible without dropping the tank. There's no external filter to change on these engines like there is with the diesel.
To be absolutely certain, you should:
1. Consult your owner's manual: This is the best source for the precise location.
2. Use a repair manual specific to your year and engine: Repair manuals (like those from Haynes or Chilton) often have diagrams showing the fuel filter location.
3. Search online for diagrams or videos: A search like "2004 Chevy HD [Engine Type] fuel filter location" on YouTube or Google Images may yield helpful results.
Don't attempt fuel filter replacement if you're not comfortable working with fuel systems. Fuel is flammable, and improper handling can lead to injury or damage.
