Lawnmower Primer Bulb Has Hole? (We Have A Fix)

How To Replace a Worn Lawnmower Primer Bulb

It is not uncommon for unvented primer bulbs to develop a hole or crack after several seasons. Venter primer bulbs can also crack or become so soft they won’t return to the up position after being pressed. In either case, replacing a worn primer bulb is easily accomplished by following a few simple steps.

Step 1: Find the Replacement Bulb

Step 2: Empty the Gas Tank on your Mower

Since you will need to disconnect and reconnect the fuel line to the primer bulb, you must empty the fuel tank before you start. Otherwise, you risk a gasoline spill and a resulting fire. Be safe when you work.

Step 3: Gather Your Tools

Step 4: Remove the Engine Cowling and the Starter Assembly

Remove the engine cowling and the starter assembly and lay them aside. We suggest that you use a magnetic parts bowl to hold the screws, nuts, and bolts. A magnetic parts bowl will keep all the small bits together and in one place.

Pay attention to the underside of the cowling where the starter coil engages the engine. There may be small cams or other parts that can shift or come loose.

Step 5: Remove the Air Cleaner

To get access to the carburetor, you must remove the air cleaner. On most small engines, the air cleaner assembly is held in place by a pair of screws on the inside bottom of the air cleaner housing. After you remover the air cleaner cover and the air cleaner, these screws should be visible and accessible.

Remove the air cleaner and set the entire assembly aside.

Step 6: Remove the Carburetor

There may be two to four screws or bolts holding the carburetor to the intake manifold. The number of bolts depends on the make and model of your lawnmower. Use the correct size wrench or socket to remove the bolts. Slide the carburetor from the intake manifold and carefully remove the fuel line.

Step 7: Remove the old Primer Bulb

You can now remove the old primer bulb. If the primer bulb on your engine has tabs, use the needle-nose pliers to squeeze the retaining tabs. You should be able to remove the old primer bulb.

On engines with a retaining plate around the primer bulb, remove the screws carefully to release the old primer bulb. There may be a small gasket under the primer bulb. You should remove the gasket as well and replace it with a new gasket.

Step 8: Install the new Primer Bulb

Make sure that the area where the new primer bulb will sit is clean. There should be no oil, dirt, or debris. Anything under the primer bulb seat can cause air leaks. Air leaks in the fuel system can cause your lawnmower engine to run poorly.

Reverse the steps you took to remove the old primer bulb to place the new primer bulb. Be careful not to damage the primer bulb or its housing. Tighten the screws on the retaining plate but done over tighten them to avoid damage.

Step 9: Re-assemble the Carburetor

Before you re-install the carburetor on the intake manifold, examine the gasket. Make sure that the gasket is intact and wasn’t damaged when you removed the carburetor. If there is any visible damage to the gasket, replace the old gasket.

Remember to put the fuel line back on the carburetor and the primer bulb before putting the carburetor back on the engine.

Step 10: Assemble the Air Cleaner

Step 11: Re-install the Engine Cowling

Re-install the engine cowling and make sure that the starter assembly engages with the engine. The starter rope should pull freely.

What Does the Primer Bulb Do?

Lawnmower Starts but then Stops?

If your lawnmower will start but then dies, you probably have a problem with the fuel system or carburetor. There are several things you should suspect if this is the case.

Check your lawnmower for any of these problems.

What is the Best Way to Start a Lawnmower?

The best way to start your lawnmower is by following the directions in the user’s manual that came with the mower. Different manufacturers have different steps for starting their lawnmowers. However, in general, you can start many lawnmowers using these steps.

Step 1: Make Sure the Area is Safe

Be sure that the area around and under your lawnmower is free of any objects that the mower might pick up and throw.

Step 2: Prime the Engine

Press the primer bulb the correct number of times. The number of presses can vary from 4 to 8 times. Follow the mower manufacturer’s directions exactly. Pressing the primer bulb too many times may overfill the carburetor and make the mower hard to start.

Step 3: Get in the Right Position

Where to stand depends a lot on your mower. Some mowers have the pull handle mounted on one side or the other. Many new mowers extend the pull rope to the handle so you can stand behind the mower.

Step 4: Pull the Rope

Pull the start rope smoothly. If your mower has a safety interlock, you may need to hold the interlock closed on the mower handle while pulling the starter rope. The engine should start after no more than two pulls.

Related Questions?

Under normal circumstances, gasoline should not leak out of your primer bulb. Even air primers that have a hole in the bulb should not leak gasoline. If you notice gasoline leaking from the primer bulb on your mower, shut the mower down and investigate the cause. Leaks from the primer bulb are a symptom of a bigger problem.

A Hole or No Hole – It May Not Be a Problem

That hole you notice in your primer bulb may not be a problem. The hole may be an integral part of the function of your fuel system. In any case, a faulty primer bulb is not a major issue and is usually a quick and easy repair. We hope that the information and recommendations in this article help you resolve your lawnmower problems.