Briggs and Stratton Primer Bulb Replacement 3.5HP

Learn how to replace a primer bulb on a Briggs & Stratton diaphragm carburetor.

Tools/Parts Required 

  • Flat Head Screwdriver
  • Replacement Primer Bulb
  • Air Compressor/Carburetor Cleaner

Step 1.

Gently pry out the clips shown in the video. Push the retaining plastic clip up, this will release the primer bulb.

Step 2

Clean underneath and clear any blockages that would cause the primer to fail.

Step 3

Install the new primer by clipping it in place, or replace old if you’re just cleaning.


  1. Thanks for posting the tutorial about replacing the primer bulb on a Briggs and Stratton 3.5HP lawn mower. It was just what I needed to help another help me in replacing one that was pierced.

  2. I broke the retaining clip –I think the guy in the video did too –there’s an edit right where I broke mine!


    • No clips were harmed in the making of this video haha! its shame yours broke they are usually quite sturdy.

    • This means that there is a blockage/problem with your carburetor, It is likely is needs to be cleaned and possibly have the diaphragm replaced

  3. Tore my carb down and cleaned and have a new bulb. There is a small steel ball and a seal/cup that fell out and have no clue where it goes. The ball is very small and the cup has a small hole in the center. Thanks for the help.

    • Hi Mike

      The ball & cup sit directly behind the primer bulb, There should be 3 holes behind the primer bulb, The cloest one to the air filter should have the cup & ball inserted.

Leave a Reply

Your email address will not be published. Required fields are marked *