Starting your mower without a functioning primer bulb is difficult, and especially so as the summer fades and days turn cooler. This video covers primer bulb replacing, a common cause of hard or no start cold starts.
Primer bulbs have an important function, they add extra gas to the engine in preparation for a smooth start. Without the extra gas, the engine likely won’t start or starts and stumbles. Primer bulbs get a ton of use and as they’re made from rubber, they perish over time. Luckily replacing the primer bulb is easy and you won’t even need to remove any components, it’s all covered in the video.
Before working on your mower be sure to remove the plug wire to prevent accidental starting, see “Repair Safety Video”.
You’ll find useful resources on this page, tips, links to tools, parts, and supplies required to complete your repair.
Tools & Parts
To nail this procedure you may need the following tools, parts, and supplies. Briggs & Stratton.
Briggs & Stratton
This is a common Briggs air filter housing with an integrated primer bulb. This kit includes the housing, gasket, and primer bulb. Very often the fault isn’t with the primer bulb itself but instead a faulty housing or gasket. Picture links to Amazon.com.
This is the first tool on the list for good reason, WD solves a ton of problems. I won’t work without it, because I can’t. Picture links to Amazon.com.
Ratchet Tool Set
Before we can do anything, we’ll need tools. I’ve selected this set as I own some Craftsman tools and while I have worn some out, they did do a lot of work. So I expect this set will last the occasional user quite a long time. This set carries both metric and standard sockets and that’s important because some mowers will have both types of fastener sizes. Set includes spark plug sockets. Picture links to Amazon.com.
Gas & Oil Syphon
You’ll find this tool really useful if you need to drain the gas tank, and you will if the gas is stale. The siphon will remove it without fuss or mess and it can be used for extracting the oil too. Picture links to Amazon.com.
Gas Line Clamp
Some small engines will have a gas tap, which is really handy when removing the carburetor, stops gas flowing all over the shop. However most engines won’t have one, these useful clamps simply squeeze the fuel line and prevent a spill while you perform surgery. Picture links to Amazon.com.
When cleaning your carburetor you’ll need this stuff. Gumming is a sticky substance that’s hard to shift. The carb cleaner will remove it, however, if your carb is really bad, save yourself some work, go ahead and buy a new carburetor. Picture links to Amazon.com.
You’ll find these nylon brushes super useful when it comes time to clean those tiny passageways of the carburetor and jet. Use these in conjunction with the WD Carb cleaner. Picture links to Amazon.com.
I use a DeWalt screw gun (also a drill) in the workshop to speed up the process of removing engine covers, carburetor bolts, Armature bolts, etc. It’s a brushless motor and as tough as nails, I drove over it a few times – still works great! Batteries are interchangeable and so if you have a DeWalt product already you won’t need the battery. Picture links to Amazon.com.