How to Clean an Outboard Carburetor: Complete DIY Guide

A dirty carburetor is one of the most common causes of outboard problems. Symptoms include:

• Hard starting
• Rough idle
• Stalling at low speed
• Poor throttle response
• Engine won't stay running without choke

The good news? Cleaning a carburetor is a DIY job that saves you $250-400 in shop labor. Here's how to do it right.

What You'll Need

• Carburetor cleaner spray
• Small screwdrivers (flathead and Phillips)
• Needle-nose pliers
• Clean rags
• Small container for parts
• Carb rebuild kit (optional but recommended)
• Safety glasses

Step 1: Remove the Carburetor

1. Disconnect the fuel line at the carburetor inlet
2. Remove the throttle linkage (take photos before disconnecting!)
3. Remove the choke linkage if present
4. Unbolt the carburetor from the intake manifold
5. Carefully lift the carb away from the engine

Pro tip: Take photos at every step. This makes reassembly much easier.

Step 2: Disassemble the Carburetor

1. Remove the float bowl (usually 4 screws on the bottom)
2. Carefully remove the float and float needle
3. Remove all jets using the correct size screwdriver
4. Remove the idle mixture screw (count turns as you remove it!)
5. Keep all parts organized – use a muffin tin or egg carton

Step 3: Clean All Passages

This is the critical step. Carb problems come from clogged passages, so be thorough:

1. Spray carb cleaner through every passage, jet, and hole
2. Use compressed air to blow out loosened debris
3. Clean jets with carb cleaner – never use wire or drill bits
4. Inspect the float needle and seat for wear or debris
5. Clean the float bowl thoroughly

Warning: Carb cleaner is harsh. Wear safety glasses and work in a ventilated area.

Step 4: Replace Gaskets and O-Rings

Old gaskets cause air leaks that create lean running conditions. If you have a rebuild kit, replace:

• Float bowl gasket
• All O-rings
• Float needle (if included)
• Accelerator pump diaphragm (if equipped)

Step 5: Reassemble

1. Install jets (snug but don't overtighten)
2. Install idle mixture screw to original position (remember your turn count)
3. Install float and needle valve
4. Check float height per manufacturer specs
5. Install float bowl with new gasket
6. Reinstall carb on engine
7. Reconnect linkages and fuel line

Step 6: Initial Adjustments

1. Set idle mixture screw to factory spec (usually 1-1.5 turns out)
2. Prime fuel system
3. Start engine and let it warm up
4. Adjust idle speed screw for smooth idle
5. Fine-tune idle mixture for best idle quality

When Cleaning Isn't Enough

Sometimes a carb is too far gone:

• Worn throttle shaft (causes air leaks)
• Damaged float
• Corroded jet passages
• Warped mating surfaces

In these cases, a rebuild or replacement may be necessary.

Prevent Future Carb Problems

• Use fuel stabilizer if the boat sits more than 2 weeks
• Run the carb dry before storage by disconnecting fuel and running until it stalls
• Use fresh fuel – ethanol fuel goes bad quickly
• Install a quality fuel filter before the carb

Get Video Tutorials + More

Want to see this process on video? BoatFix Pro members get access to step-by-step video tutorials for every common repair, plus our Emergency Troubleshooting Checklist and private Android app.

Start your membership for $14.99/month →