How to Clean a Carburetor on a Generator?

Do you have a generator that’s not running right?

A dirty carburetor is often the culprit. This article will teach you how to clean your generator’s carburetor, so it runs like new again.

You don’t need to take your generator to a mechanic and pay for expensive repairs. With this guide, you can clean your generator’s carburetor yourself in just a few simple steps.

Read till the end and learn how to clean your generator’s carburetor!

How does a Carburetor work?

Let us briefly introduce you to the working of the carburetor so that you are able to appreciate problems in their operation and the troubleshooting steps. A partial vacuum is created during the downward stroke of the engine piston.

The differential between the atmospheric pressure and this negative pressure induced by the engine drives the fuel through the jets. This fuel is atomized into a fine mist, ready to vaporize. All modern carburetors have automatic mixture control features.

You require an air-to-fuel ratio of about 6 or 8 parts of air to one part of gasoline during a cold start and 10.5 or 12 parts to 1 at full rated power after the engine has warmed up. The engine actually requires a ratio of 14.6 to 1, but small engines use some of the fuel to cool themselves.

The air (at high pressure, low velocity) passes through the air filter and crosses a narrow passageway known as the bore or the venturi, where it gains velocity at the expense of pressure. This low pressure allows it to suck the fuel from the main jet (mounted inside the main discharge tube), located at the venturi throat. The carburetor has three modes of operation – the normal mode, during cold conditions, and the idle mode. Let us see the difference between the three modes.

  1. The Normal Mode or the High-Speed mode: As already discussed, the choke is in an open position, and the fuel is drawn from the main jet. Both mix at the throat of the venturi, where the high-speed air converts it into a mist. The mixture passes through the throttle plate to the cylinder.
  2. The Idle Mode: The throttle plate is fully closed. The fuel is drawn through the idle port opening, which is located beyond the throttle plate, and controlled by an adjustment screw. As the throttle plate opens, more ports are opened to increase the fuel flow. You can understand the idle operation in this informative video.
  3. The Cold Engine Mode: The choke butterfly is closed, and the full length of the generator carburetor bore is under vacuum and draws fuel from the main jet, idle port, and idle jet, with minimal air to send a rich fuel mixture to the engine.

Symptoms of a Carburetor in Need of a Cleaning

Various symptoms to alert you that your generator carburetor needs cleaning are:

  1. The generator won’t start; you have fresh fuel and no problems with the air filter and spark plugs.
  2. The engine runs when the choke is closed, or half closed but stops or runs rough when you open the choke.
  3. Flooding of the carburetor bowl or no fuel in it.
  4. The engine runs roughly in idle mode.
  5. The engine is running lean.

Common Carburetor Problems

Most of the above symptoms will lead you to the following common problems, which clearly indicate the accumulation of dirt and/or clogging of fine openings, ports & jets, or the movable parts getting stuck due to the gum formation.

  1. Clogging of the main jet and/or the emulsion tube.
  2. B. Float Needle is stuck in open or closed positions or has an improper seal.
  3. C. Clogging of Pilot/Idle jet.
  4. Air leak downstream of the carburetor.

In most cases, these problems can be traced back to the storage of fuel in the fuel tank and the carburetor beyond the recommended period without the use of a prescribed fuel stabilizer. The only solution is to deep clean the carburetor before using it again. Let us explain to you how.

How to Clean a Generator’s Carburetor?

Before we dive deep into the actual cleaning process, let us quickly run through the list of tools, parts, and materials required to carry it out.

Carburetor Cleaner

In the past, dip-type cleaners were used. However, the presence of plastic parts in the modern carburetors precludes their use anymore with certain exceptions. Hence the choice is between chlorinated, non-chlorinated, and aerosol-based carburetor cleaner.

  • Chlorinated: These types are banned in many states, including California, due to the presence of volatile organic compounds.
  • Non Chlorinated: Less toxic than the chlorinated option but highly flammable. They don’t dry as fast but are safe to use on plastic components.
  • Aerosol-based: These are marketed as spray cans. They require more force than any other carb cleaner. However, the liquid cleaner and the air propels it to reach small openings.

If you check their data sheets, you may find the use of chemicals like toluene, methyl alcohol ketone (MEK), which may cause blindness, skin irritation, heart-related issues, etc, with long exposures.

While using them for carburetor cleaning, be careful and work in a well-ventilated area. There should be no ignition source in the vicinity, and ensure you use personal protective equipment (PPE) like a face shield or goggles with side shields and gloves. It is even said that toluene and MEK can pass through the skin and reach the internal organs.

Some DIY enthusiasts also recommend the use of white vinegar or lemon water for boil cleaning the float type carbs. They give decent results but are too acidic, and if any trace is left in the carb, it will corrode quickly.

Materials Needed

In float-type carburetors, the needle seat and the inlet needle are the only parts that may wear out, mostly due to varnish and corrosion. In addition, the only parts that you will ever need to keep are carburetor body mounting flanges, air cleaner gaskets, and float bowl ring gaskets.

However, in the diaphragm-type carbs, soft parts like the diaphragms and other gaskets also should be replaced whenever you are opening them.

You get two types of carburetor kits

  1. The basic kit carries diaphragms, gaskets, O rings, needle, and seat assembly.
  2. The comprehensive kit has all the parts except the casting.

Tools Needed

Various tools needed are:

  1. Narrowly focused and powerful light source.
  2. A flat head screwdriver with a narrow blade.
  3. 10mm Combination wrench or socket set. Other sizes may be required depending on the size of the bolts on your unit.
  4. Nose pliers.
  5. A soft-jawed vice.
  6. A small ball peen hammer,
  7. A fine-stranded copper wire to clean the small ports and jets.
  8. A wire brush, and
  9. A paper towel or shop rags.

Steps to Clean a Generator’s Carburetor

With all this background and preparation, you are now ready actually to clean out your generator carburetor and improve its performance.

A. Removing The Carburetor

Let us start by first removing the carb from the generator.

  1. Start by closing the fuel valve to shut off any further supply from the fuel lines.
  2. Disconnect the fuel line connected to the carburetor.
  3. Disconnect the spark plug lead. Clean the area around it for any debris and remove the plug.
  4. Remove the air filter cover and the air filter. Then remove the nuts, any connected hoses, followed by the gasket between the filter assembly and the carb.
  5. Drain any residual fuel in the carburetor bowl into an appropriate container by opening the drain bolt with the help of a 10 mm wrench or socket. Check your owner’s manual before doing it for the exact arrangement in your generator.
  6. Next, disconnect any wiring, and detach the springs (with long-nosed pliers) and the linkages. Make a note or a sketch of where these springs and linkages connect to.
  7. Open and remove the two mounting screws securing the carburetor to the engine. You might have to twist it a little to disengage the wires.

B. Dismantling and Inspecting Inside Parts of the Carburetor

In this stage, you should examine the carburetor assembly for damages requiring immediate attention and try to pick early signs of potential issues that may lead to a failure at a later time.

  1. Examine the gasket between the carburetor and a generator body. Replace if damaged. Otherwise, it is a potential source of air leaks, causing vacuum destruction and lean air operation.
  2. Examine other gaskets and O rings. Look out for dark strains caused by the leaks.
  3. Try to feel the condition of the carburetor bore by running your finger. If it has sand or dirt, it indicates failure of the air filter or leakage from the gasket.
  4. Remove the bowl by unscrewing the 10mm bolt at the bottom. Check for the condition of the gasket around the bolt area and action accordingly. Any deposits in the bottom area or under the metering diaphragm cover will highlight the condition of the internal circuitry. The presence of varnish or very light rust can be tackled, but you must look out for any water-induced corrosion. You may need to buy a new carburetor if you find it with severe damage.
  5. Use a flat head screwdriver of the appropriate size to remove the main jet from the distribution tube. Do not apply more force as the main jet is made from a very soft material and may get damaged. Remove the emulsion tube, connected to the main jet. Some emulsion tubes are held by two O rings, and removing them in a small space is a bit of a struggle.
  6. Now take out the float valve by removing its pin. Inspect the condition of the float needle. Some generators have rubber-tipped needles, while some have a rubber O ring. Deformity in the rubber is a sign of improper operation of the float. Check if the needle is getting stuck in a closed or open position due to varnish and gum formation. If it is stuck in the closed position, it will not allow any passage of fuel, while there may be a flooding of the engine if it is stuck in an open position.
  7. Remove the throttle adjustment screw. Note down the number of turns to unscrew it. You will find the pilot / idle jet below this adjustment screw. Use the flat head screwdriver to remove it.
  8. Now remove the air mixture adjustment screws. Again note down the number of turns to unscrew it. You run the risk of distorting the seats and the tapered needles if you turn more while screwing it back.
  9. Lastly, examine the main jet, emulsion tube, and idle jet for any clogged holes. If the main jet is fully clogged, it will not allow the engine to start. In partially clogged conditions, the engine may shut down when the choke is opened. A blocked idle jet will result in the rough operation of the engine in idle mode.

C. Cleaning The Carburetor

We have already dismantled the carburetor to expose every fuel and air passage. Dismantling the throttle and choke butterfly is not needed and should be left to experts if required.

  1. Start by cleaning the external surfaces when a solvent.
  2. Use carb cleaner, wire brush, or hand cloth to clean the carburetor bowl. Start by spraying the cleaner and then wipe it clean.
  3. Spray the carb cleaner with the straw into the aperture of the carb nozzle. You can use a thin wire, needle, or finely-stranded copper wire to remove any debris from the aperture.
  4. Repeat the process through every hole, jet, and emulsion tube, including pinholes at the bottom of the jet.
  5. Spray the carb cleaner on the needle seats in the open and closed position, the distribution tube, the air mixture screw hole, etc.

D. Re-attaching The Carburetor

Follow the reverse order to reassemble your carburetor, and be careful to ensure that no dirt or dust enters it during fixing it back. Use your notes, sketches, and information about the number of turns so that everything is in order after fixing, and you do not need to open it again. Few words of caution:

  1. While you may need some sealant to fix your gaskets, do not use ones that will permanently stick and destroy the gaskets; if you ever open the carburetor again.
  2. Do not use silicon-based sealants as they dissolve in gasoline.
  3. Do not use any threaded fittings with the Teflon tape, as you can get stripped threads that may enter the jets and block them.

Steps to Ensure a Clean Carburetor

To ensure that you don’t land up in these kinds of situations often, you need to do the following:

  1. If you do require a generator in the near future and are moving it to the storage area, close the fuel valve.
  2. Do one of the following; (a) Run the generator for 15 minutes every month and load it for a few minutes, (b) Add a fuel stabilizer (c) Drain the fuel from the generator.
  3. Do not use ethanol-blended gasoline, as it can eat the gaskets, absorb ambient air moisture, and support corrosion.


In this blog post, we have discussed how a carburetor works, the symptoms of a clogged carburetor, and how to clean a generator’s carburetor. We also discussed some regular maintenance steps related to the carburetor. Please let me know in the comments section below if you have any questions or need clarification on any of the information in this blog post. Thanks for reading!

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