Yamaha Outboard Carburetor Cleaning | Yamaha 90 Carburetor Rebuild | Boats.net

Introduction

This tutorial will guide you through the process of cleaning and rebuilding the carburetors on a Yamaha 90 outboard motor. Proper maintenance of the carburetors is essential for optimal engine performance and longevity. This step-by-step guide is derived from a detailed walkthrough, ensuring you have the information you need to complete this task effectively.

Chapter 1: Removing Carburetors

1. Accessing the Carburetors

   • Locate the two latches on your outboard—one at the front and one at the back.
   • Unlatch them to lift off the cover.

2. Remove the Silencer Cover

   • Use a Phillips head screwdriver to remove the four bolts securing the silencer cover.
   • Lift the cover off.

3. Unbolt the Carburetors

   • Use a 10mm socket to remove the bolts holding the carburetors in place.
   • Take note of the ground wire attached to the lower bolt. Ensure it is not tucked under the tank during reassembly.

4. Disconnect the Linkage

   • Remove the linkage by popping off the pins with gentle pressure.

5. Disconnect Necessary Lines

   • Remove the vacuum line and two hoses from the back of the engine.
   • For stuck fuel hoses, use needle nose pliers to gently twist them to break the seal.
   • Disconnect the electrical connections from the carburetors.

Chapter 2: Disassembling Carburetors

1. Prepare for Disassembly

   • Set up a clean work area with a drain pan and carburetor cleaner.

2. Inspect and Separate Fuel Lines

   • Carefully detach the fuel lines from each carburetor to avoid damage.

3. Clean the Exterior

   • Spray the outside of the carburetors with carburetor cleaner to remove debris.

4. Remove the Float Bowl

   • Use a soft blow hammer on the screwdriver to loosen any corroded screws.
   • Carefully lift off the float bowl.

5. Inspect Internal Components

   • Remove the gasket and inspect it for damage.
   • Lift out the float and float needle for inspection.

6. Replace Damaged Parts

   • If the float needle shows pitting or damage, replace it.
   • Inspect the float for cracks or breaks.

Chapter 3: Cleaning Jets and Reassembling

1. Remove and Clean Jets

   • Use penetrating oil to loosen any seized jets.
   • Remove the pilot and main jets, inspecting for clogs.

2. Flush Jets

   • Spray carburetor cleaner through the jets to ensure they are clear.

3. Reassemble the Carburetor

   • Install the pilot screw by screwing it down until it bottoms out, then back it off 1.25 turns.
   • Reinsert the pilot and main jets, ensuring they are snug but not overtightened.

4. Install New Parts

   • Add new O-rings to the float seat and ensure they are correctly seated.
   • Reassemble the float with the new needle and clip.

5. Secure the Float Bowl

   • Place the float bowl back on and tighten the screws.

Chapter 4: Reinstalling the Carburetor Bank

1. Replace Broken Fuel Line

   • Cut a new piece of quarter-inch fuel line to replace any damaged sections.

2. Reinstall the Carburetors

   • Start with the top carburetor to support the others during installation.
   • Reconnect all hoses and electrical connections.

3. Reconnect Linkages

   • Ensure both throttle and oil injection linkages are properly reattached.

Conclusion

By following these detailed steps, you can effectively clean and rebuild the carburetors on your Yamaha 90 outboard motor. Regular maintenance will help prevent issues and keep your engine running smoothly. If you need parts for your project, visit Boats.net for a comprehensive selection. Don’t hesitate to ask questions or leave comments for further guidance. Happy boating!