How to Change the Fuel Filter on a 1991 GMC Sonoma

The fuel filter on the1991 GMC Sonoma is the most important part of the fuel cleaning process. The fuel filter traps the sediments from the fuel inside of the fuel filter. The fuel leaves the gas tank and goes into the fuel filter. From the fuel filter, the fuel is cleaned and sent out the other side to the engine. You can replace the fuel filter on the 1991 GMC Sonoma in less than an hour.

Things You'll Need

• 5/8 Open end wrench
• Fluid catch pan
• New fuel filter

Instructions

1. Park the truck on a even surface and turn the engine off. Unscrew the gas cap from the gas tank to relieve the pressure off of the fuel filter.

2. Locate the fuel filter under the driver side of the truck. The fuel filter on the 1991 GMC Sonoma inside of the frame rail between the driver side cab and the fuel tank on the driver side. The fuel filter is inside of a round plastic bracket.

3. Loosen the fuel lines that are going into the fuel filter with a 5/8 wrench. Put the 5/8 wrench on the hex head of the fuel line and turn the hex head counter clockwise to loosen the fuel line. Slide the fluid catch pan under the fuel filter before completely removing the lines from the fuel filter. Finish unscrewing the fuel lines from the fuel filter and let the little bit of excess fuel run into the catch pan.

4. Slide the fuel filter out of the round plastic bracket. If needed, bump the fuel filter with your hand to loosen it from the plastic bracket. Discard the old fuel filter into the fluid catch pan. Then slide the fuel filter out of the bracket. Slide the new fuel filter in the plastic bracket with the flow arrow pointing towards the engine.

5. Screw both of the fuel lines back into the fuel filter. Insert the fuel lines into each end of the fuel filter and turn the hex heads clockwise to tighten. Then take the 5/8 wrench and tighten the fuel lines down so that each line is very tight. Then slide the fluid catch pan out from under the truck.

6. Screw the gas cap back on the engine. Then turn the ignition key on and off three different times to prime the fuel filter. Then crank the engine.

7. Inspect the fuel filter and fuel lines for leaks while the engine is running. Then turn the engine off.

Tips & Warnings

• The flow arrow on the fuel filter represents the flow of the fuel through the fuel filter. The arrow must point towards the engine and away from the gas tank.

• Always wear safety glasses when working around fuel.

References

• Haynes Repair Manual: 1988-1998 GMC Sonoma Pick Ups: John Haynes-Updated Version: 2005

Resources

• 2 Car Pros: GMC Sonoma Repair Questions and Answers