Three Types of Briggs and Stratton Carburetors and How to Troubleshoot Them

Engines require functional and well-maintained carburetors to operate smoothly. If you have a Briggs & Stratton engine, it’s necessary to know the type of carburetor it features. Doing so can help in troubleshooting most carburetor-related issues.

Below we’ll discuss the three types of Briggs and Stratton carburetors, including what makes them unique. Then we’ll take you through troubleshooting these carburetors to keep your engine running correctly.

Briggs and Stratton Carburetor Types

Briggs & Stratton uses three types of carburetors for their engines. Their carburetors can have the following:

• Primer system
• Manual choke system
• Auto-choke system

Let’s discuss these carburetor types and how they work.

Primer System

The primer system is common in small Stratton and Briggs engines. It’s a small plastic bulb featuring a hose that runs through it. When pressed, the primer draws gas from the pump’s fuel chamber and feeds it into the carburetor.

The primer system will pump the required fuel amount into the carburetor. This process allows the carburetor to create a proper fuel-to-air ratio needed in the cylinder.

So, why do small engines require carburetors with a primer system?

Unlike larger engines, Briggs & Stratton small engines don’t have fuel injectors. They rely on the engine force to pump the fuel mixture into the combustion chamber. When the engine is off, gas can seep out of the carburetor and cause starting difficulties.

The carburetor needs the primer system to be filled with fuel to start the engine.

Manual Choke System

Some Briggs and Stratton carburetors can come fitted with a manual choke system to supply a richer fuel mixture into the combustion chamber.

A flexible cable extends from the operator’s compartment to the choke plate. Pulling the control (knob) out closes the choke plate to supply a rich mixture. Pushing the control back in adjusts the choke plate for a balanced fuel-to-air mixture.

The manual choke system helps a cold engine to start properly. A cold engine makes fuel condense and results in fuel flow problems. The manual choke system ensures the combustion chamber receives a richer mixture with enough vapor. As the engine attains operating temperature, the choke system gradually supplies a less rich mixture.

The manual choke system has a poppet and choke valves to prevent fuel from flooding the combustion chamber.

Auto-Choke System

The auto-choke system is more common in Briggs and Stratton carburetors. Unlike the manual choke, the auto-choke system engages and disengages itself to regulate the air and fuel mixture.

When you turn on the ignition key, power from the battery activates the auto-choke to allow the engine to receive a richer fuel mixture. This process allows the engine to start smoothly, particularly in cold weather.

Once the engine reaches operating temperature, this choke deactivates itself to allow the correct air-to-fuel ratio.

How to Troubleshoot Briggs and Stratton Carburetors

There are various ways to troubleshoot the three types of Briggs and Stratton carburetors. In most cases, carburetor problems occur due to poor maintenance.

The carburetor might have minor issues, such as adjustment or blockage problems. It’s necessary to check the carburetor’s condition to know if any troubleshooting and fixes are required.

Luckily, problems with Briggs & Stratton carburetors will manifest in the following ways:

• Engine starting problems
• Engine losing power
• Engine overheating
• Engine hesitating when accelerating
• Exhaust emitting black smoke
• Engine backfiring

Let’s see how to troubleshoot your carburetor.

Carburetor Adjustment Problems

A misadjusted Briggs and Stratton carburetor can result in engine starting problems. If your engine has a misadjusted carburetor, you’ll need to adjust the speed and fuel mixture. Check your specific engine’s manual to understand how to adjust the carburetor.

Dirty or Corroded Carburetor

Dirty, contaminated, or old fuel can clog up the fuel line, including the carburetor. When the carburetor gets clogged, it fails to supply the correct air-to-fuel mixture into the combustion chamber. As a result, the engine might fail to start, lose power or backfire.

The best way to troubleshoot a dirty or corroded carburetor is by cleaning it. Flushing a cleaning solution into the fuel line and running the engine might not remove all the clogs in the carburetor. So, remove the carburetor and clean it.

Check the jets, passageways, or channels for clogs or corrosion. A soft bristle brush will help remove corrosion from your carburetor. If clogs are on the passageways, use compressed air to remove them. Then spray a carb cleaner to remove clogs or dirt on the carburetor.

When reinstalling the carburetor, buy a carburetor rebuild kit, as you might not reuse the old gaskets and seals.

Remember that you’ll need to clear any clog in the fuel line to prevent the issue from recurring. So, drain the old or contaminated fuel and inspect the lines for deposits or clogs. Flush a carb cleaner through the lines and replace the fuel filter.

When adding fresh fuel to the tank, mix it with an effective additive to keep the gas in good condition longer.

After cleaning the fuel line, check the spark plug and air filter to see if they’re defective. Clean a clogged filter or replace it if it’s old or worn. 

Next, check the spark plug and secure it if it’s loose. You can also remove it to see if it’s dirty or blown out. Replace the plug if necessary.

Damaged or Old Carburetor

With time, the three types of Briggs and Stratton carburetors can wear out and fail to work. So, what should you do if you clean and adjust the carburetor but it fails to work?

Uninstall the carburetor and check for any defects. If the carburetor problems result from permanently clogged or damaged parts, you can replace them. However, if rebuilding your carburetor won’t resolve the problem, replace it.

Adjust the new carburetor and start the engine. If your engine fails to start after installing a new carburetor, there might be other issues with the fuel system or the engine. In this case, you can allow a professional mechanic to diagnose and fix the problem.

Final Thoughts

This article helps you know the three types of Briggs and Stratton carburetors. These carburetors might be in lawnmowers, generators, or hedge trimmers with Briggs & Stratton engines.

If your engine has carburetor-related issues, you can use our troubleshooting guide. Clean the carburetor and adjust it to see if the engine will run properly. If the problems persist, repair or replace the carburetor. Lastly, regular carburetor maintenance will prolong its lifespan and keep the engine at its tip-top quality.