How to clean outboard carburetor without removing?

Last Updated on October 1, 2022

You may have wondered how power is generated in gas engines, or how gas or fuel is converted and probably what converts it into such power that allows it to move or work? Well, the secret is in the combustion house of the boat. This combustion house is the boat carburetor.

The carburetor in a boat assumes a very important part of the entire gas engine. It is the powerhouse of combustion, which is the mixing of the right amount of fuel and air which is then sucked into the engine to produce power that enables the engine to run.

There is the inboard and the outboard boat carburetor. In inboard motors, the rudder, shaft, and propeller go underneath or inside the boat. Its maintenance would demand that it is first removed.

The outboard motor is very popular on fishing boats and pleasure boats. It is self-contained, that is, it has the propeller, engine, and steering control all in one unit and is attached to the back wall of the boat. This is convenient because you can lift the whole unit out of the water when you winterize your boat.

The grass, the twigs and other debris that a small engine encounters on course can accumulate and clog the outboard carburetor, leading to malfunctioning or total stop altogether. As a result, it needs regular maintenance, the most common of which is cleaning.

The best way to clean your carburetor is to remove and disassemble the parts to be able to have holistic access to the nooks and crannies. This can actually be very tasking, time-wasting and budget gulping.

In this article, to help you save time, money, and energy, we explore how you can clean your outboard carburetor without removing it.

First, you need to be sure that your carburetor is faulty for being clogged or dirty. Secondly, you need to know the best cleaners to use for this. Thirdly, you need to know the different methods and how to go about this cleaning given the necessary materials.

To be able to clean the Carburetor without removing it, we need to know the symptoms of a faulty carburetor and the materials you need for the cleaning.

Basic symptoms of a faulty carburetor.

  • A faulty carburetor may likely not just start although it may turn over or crank. This can be caused by too much dirt. This affects the required combination of air and fuel traveling through the passage to the engine.
  • Your boat engine may run lean. An engine “runs lean” when there is an imbalance in the appropriate ratio of fuel and air. This causes sneezing or popping sounds in the intake.
  • A faulty carburetor can also lead to a boat engine running rich. This is the exact opposite of running lean, meaning there’s excess fuel and not enough air. This can lead to black smoke coming from the exhaust.
  • A faulty carburetor floods. This happens when there is dirt or debris in the fuel bowl, leading to a blockage of the needle valve and preventing it from closing. Fuel will automatically overflow into the carburetor, causing fuel to flow out of the bowl vents, and leading to an imbalance in the air-to-fuel ratio, and getting the spark plugs wet.

How to clean the outboard carburetor without removing

For the purpose of illustration on how to clean the the Carburetor without removing,

the B12 Carburetor and a few other cleaners will be used for a step-by-step guide below.

B12/Berryman b12 Carburetor Cleaner

The B12, like most other cleaners, dissolves gum, varnish, fuel residues, and other deposits from the carburetor, PCV valve, automatic choke, carburetor linkage, throttle body, and distributor shaft. For a step-by-step guide,

  • Blending: blend 4 oz of the B12 with a full gasoline tank and pour the B12 carb cleaner into the tank.
  • Undertake a slow ride, so the carb cleaner flows through the idle system.
  • Ensure high RPM is avoided while the B12 carb cleaner is in the gas tank, to avoid washing the oil off the cylinder walls.
  • You can ascertain that the carb cleaner has done its job once the RPM rises.
  • To confirm a thorough clean-up after using B12 carb cleaner, let some aerosol B12 into the carb’s intake mouth through the pilot air jets located beneath the big vacuum diaphragm.

The use of Seafoam

The seafoam is an excellent product in the form of a spray, which functions by dissolving grime and carbon off the carb and leaves only an oily film.

For carbs that are rather gummed up, allow it to soak in a lacquer thinner before applying the seafoam spray. Users are advised to apply these products in ventilated areas because the fumes are quite hazardous.

The use of Powertune

The powertune is sprayed directly into the carb’s throat with strict adherence to the specific instructions indicated on the product.

Carburetor cleaners can also come in other convenient spray cans for periodic cleaning of both inside and outside the carburetor without necessarily removing them. Some of these other cleaners include:

  • Gumout Jet Spray: It cleans away gum, varnish, and dirt buildup on all unpainted metal parts of the carburetor which may cure rough idling, hard starting, stalling, and lost performance.
  • Berryman 0117 CB-12: This solution contains Berryman’s patented “High Energy Solvent Technology” for cleaning the internal parts of the carburetor.
  • 3M 08867 throttle plate and carburetor cleaners: This is designed for both throttle bodies and carburetors and can serve for all makes and models.

In using any of the above-discussed carburetor cleaners, ensure that rubber and plastic parts of the carb do not come into contact with the carb cleaner. This is because they might get destroyed by the cleaners.


For a full, entire, and complete cleaning of the outboard Carburetor, total disassembling is advised, especially when the fault persists after the light cleaning.

However, if the time and budget isn’t there, the above-described cleaners and methods can be applied for light cleaning too.