Briggs and Stratton Throttle Spring Diagram

The Briggs & Stratton throttle return spring is an important component that controls the speed of the vehicle or machine. This component is found in vehicles that do not use electronic throttle control (ETC) and it performs the same function in a mechanical form. The throttle return spring is vital in the vehicle acceleration thus malfunctions can be very dangerous. If there is a malfunction of the throttle return spring, it can result in unintended acceleration.

In this post, you will find a detailed Briggs & Stratton throttle return spring diagram. We also included a guide on how to correct throttle return spring problems.

Briggs and Stratton Throttle Spring Diagram

briggs and stratton throttle spring diagram 1

briggs and stratton throttle spring diagram 2

How a Throttle Return Spring Works

Some vehicles make use of a throttle cable that runs from the back of the accelerator pedal to the throttle body or carburetor. When the pedal is pressed, the throttle cable will pull the butterfly valve on the carburetor or throttle body to allow more air to enter the engine.

Taking your foot off the pedal will cause the butterfly valve inside the carburetor or throttle body to spring closed to its resting position. This helps to control the speed of the machine. If the throttle spring is broken or worn out, the throttle may stick wide open.

Depending on the vehicle, the throttle return spring is attached to the carburetor, throttle body, or throttle cable. Depending on the year of the vehicle, the throttle spring may have multiple stages so that if one part of the spring is worn out or damaged, there will be a backup to keep the throttle closed and prevent a dangerous situation.

Signs of a Faulty Throttle Return Spring

Engine RPM remains high after lifting off the accelerator

The function of the throttle return spring is to return the throttle to a closed position. If the spring is worn out or damaged, the throttle body will remain open. If the engine is running it will create a vacuum that will want to draw air into the intake making it difficult for the throttle blades to close on their own.

You will notice that the engine’s RPM will stay the same even after you let off the gas pedal. While you’re driving, this could cause you to panic, however, it can be corrected by driving the pedal manually using your foot. Also, gravity can take over and help close the throttle.

You could switch to the manual transmission, press the clutch pedal in and shift the vehicle into neutral. This allows you to stop safely. You can also perform something similar if you have an automatic transmission.

Shift the neutral gear and apply pressure to the brake pedal which will bring the vehicle to a stop. When the vehicle stops, you should turn off the engine and have it towed. It’s not safe to drive the vehicle until you have it inspected by a professional.

Gas pedal feels spongy

While the main function of the throttle return spring is to bring the throttle back to the closed position, it will also provide some strength to the throttle pedal. This is very important in older vehicles with a mechanical throttle linkage, the throttle return spring will keep the pedal in place allowing you to control it with ease.

If you depress the pedal and notice that it feels spongy all of a sudden, you could be dealing with a broken throttle return spring. In some cases, it could be that the spring is wearing out so you won’t notice any significant changes in the vehicle’s performance.

However, this is something you should check out immediately before it gets any worse.

Gas pedal doesn’t return to its normal position

You might not easily notice that the gas pedal feels spongy when depressed but you can easily notice that the gas pedal doesn’t return to the normal position. If you release your foot from the accelerator and the gas pedal doesn’t return to the normal position, then it is likely that the throttle return spring is damaged and needs to be fixed. This is a very serious problem so you should have it looked into immediately.

How to Replace a Throttle Return Spring

You might be better off allowing a local certified mechanic to inspect the throttle return spring and make any necessary checks and repairs if any is needed. To replace the throttle return spring, you will need:

  • Your engine manual or a repair manual for your vehicle type. This can be found online from your manufacturer’s website or from other online sources
  • Needle nose pliers
  • Protective gloves
  • Safety glasses
  • Replacement throttle return spring

Step 1: The throttle return spring can be found on the side of the carburetor. Locate the throttle spring and check if it is damaged. You should confirm that it is actually damaged before going ahead to replace it.

Step 2: Remove the wing nut using your hand and then remove the air cleaner and air cleaner assembly from the carburetor.

Step 3: Disconnect the damaged throttle return spring by unhooking it at both ends. You will need to use the needle nose pliers for this.

Step 4: Connect the new throttle spring using the needle nose pliers. Hook it through one of the two eyelets and stretch and pull it through the second eyelet.

Step 5: Reinstall the air cleaner assembly and secure it with the wing nut.

How Long Does a Throttle Return Spring Last?

Throttle spring issues are not common but are very serious problems that should be looked into immediately they are noticed.  The throttle return spring like many other smaller components of a vehicle is meant to last the lifetime of the vehicle. You’re less likely to replace the spring until the vehicle completely breaks down or is sold off. However, the throttle return spring can start to wear, break, and become damaged with use.

If you’re not familiar with such repairs, you might want to get your local mechanic to check out the carburetor. Gas pedal issues are not only caused by throttle return spring damages so you might want to inspect other parts of the vehicle before replacing the throttle return spring.


  • Keith Rowland is a seasoned electrician who enjoys fixing faults in home appliances and electronics. Being someone who loves writing, he shares on this blog, DIY tips on how to fix various devices within a few minutes. When he's not fixing stuff or writing a new blog post, he's playing with his two cute girls and their mom.