Briggs And Stratton Leaking Gas Out Of Air Filter? (Fix It Now!)


Briggs and Stratton Leaking Gas Out of Air Filter

Your trusted and reliable Briggs and Stratton engine is showing signs of trouble.  You have noticed gas leaking around the air filter.  You begin to wonder if it is time to replace that old engine with a new one.

Gas leaking around the air filter on a Briggs and Stratton engine is often a sign that the carburetor needs work or that the fuel shutoff valve is not closing properly.  The carburetor’s problems can include issues with the float, the needle valves, or a bad float bowl seal.

You can remedy most of these issues with a local parts store trip and a little time.  Let’s look at some of the most common problems that cause gas leaking around the carburetor or air filter.  The fix for most of these problems takes a few simple steps.

Be Cautious Before Your Start

The gasoline in your Briggs and Stratton engine is highly flammable.  All it takes is a spark to get a good fire going in a hurry.  Taking a moment to keep yourself safe is always a good way to start any project.

Before you do anything else, unplug the wire from the spark plug.  It is unlikely that the engine will start without a sharp tug on the starter rope, but some electric start can kick over without warning.

You should always work on gas-powered equipment in a well-ventilated area.  The fumes from the gasoline are dangerous.  If gasoline vapor concentration in the air gets to a certain point, almost any spark or flame will ignite the vapor.

The Most Seen Reason Gas Leaks Around the Air Filter on a Briggs and Stratton Engine

You are mowing along, and the lawnmower begins to bog down and then dies.  The mower is obviously choked with grass clippings.  The natural tendency is to tip the mower on its side and clear the blockage.

When you tip the mower on its side, gasoline can flow from the carburetor into the air filter.   You have saturated the air filter on your Briggs and Stratton engine with gasoline. The liquid gasoline leaks out of the air filter housing and prevents your mower from starting.

The Fix in This Instance

It is never a good idea to tilt any Briggs and Stratton powered equipment on its side.  You can spill grass and if the engine is hot, start a fire.  The oil in the engine can run back up into the cylinder and foul the spark plugs.

The easiest fix for this problem is don’t tilt the mower.  If you forget and find yourself with a Briggs and Stratton engine with a saturated air filter, you two choices.  You can wait for the air filter to dry or replace the air filter and restart the engine

The Fuel Shut Off Valve that Won’t

Most newer Briggs and Stratton engines have a fuel shut off valve.  The valve is in the gasoline line between the carburetor and the fuel tank.  Briggs and Stratton recommend that you shut this valve to stop the engine.  After a couple of seasons, these plastic valves may begin to leak.

Repairing a leaking fuel shutoff valve is relatively easy and straight forward.

Step 1 – Get the Parts

Visit your local Briggs and Stratton parts dealer and pick up a replacement.  Be sure and take the model number and the serial number of your Briggs and Stratton engine with you to the parts dealer.  Having these numbers will ensure that you get the correct part.

Step 2 – Gather your Tools

The tools you need will vary from model to model.  In general, you will need the following at the minimum.

  • Screwdriver or nut driver to remove the engine housing.
  • A pair of pliers to remove and replace the squeeze clamps on the fuel line
  • You will need a small dish or bowl to catch the small amount of gasoline that may leak from the fuel line.

Step 3 – Empty the Fuel Tank

Emptying the fuel tank can be tricky.  The safest way to empty the gas tank on a Briggs and Stratton engine is to start the engine and let it run.  The gasoline will eventually be exhausted, and you will have a relatively dry gas tank.

Trying to drain the gas tank into another container can be dangerous.  You aren’t saving anything.  Once you pour the gasoline into an open container, don’t put the gasoline back into your Briggs and Stratton engine. It may be contaminated and do more damage to your Briggs and Stratton engine.

Step 4 – Remove the Fuel Shutoff Valve

The fuel shut off valve is held onto the fuel line by two small spring clamps on each side of the valve.  Use your pliers to squeeze the ears on the clamp.  Slide the clamp up the fuel line away from the fuel shutoff valve on your Briggs and Stratton engine.

Work the fuel line back and forth until you can pull the fuel line off the broken fuel shutoff valve.

Step 5 – Inspect the Fuel Lines

Now is a good time to look at the fuel lines.  These short rubber tubing pieces can crack or otherwise deteriorate due to age, vibration, and the heat they endure close the Briggs and Stratton engine.

If the fuel line shows any sign of cracking or brittleness, you should replace both fuel lines to prevent future problems.

Step 6 – The Clamps, Replace or Re-use?

Your new Briggs and Stratton fuel shutoff valve probably came with new clamps.  If so, remove the old clamps from the fuel lines and put the new clamps back on the fuel lines. The old clamps may have lost some of their tension and could be a leak problem

Step 7 – Install the New Fuel Shutoff Valve

Push the fuel lines back on the barbed fittings on the new fuel shutoff valve.  Make sure you orient the valve properly so that it easy to access and operate with the engine cowling is replaced.  Move the spring clamps back to their positions close to the fuel shutoff valve.

Step 8 – Give it Some Gas and Crank it Up

Refill the gas tank with fresh gas and open the fuel shutoff valve.  Give the fuel a few seconds to fill the float bowl on the carburetor.  Don’t forget to connect the spark plug wire back to the spark plug.  Give the rope a pull, and you should be back on the road.

Other Problems That May Occur

Other problems with the carburetor on your Briggs and Stratton engine may cause gas leakage around the air filter.  Gas leaking from the float bowl of your Briggs and Stratton engine carburetor is a more serious issue.

Float Bowl Problems

The float bowl on the carburetor may have a bad seal ring.  If the seal ring on the float bowl is cracked or broken, gas leakage may occur.  A bad seal ring is easily replaced on most Briggs and Stratton engines.  However, a few Briggs and Stratton engines now have sealed carburetors that can’t be opened for maintenance or repair.  The only recourse is to replace the entire carburetor.

Carburetor Float Issues

The float inside the carburetor bowl on your Briggs and Stratton engine can stick.  A stuck float usually happens after the engine has been in storage. Gasoline left in the carburetor for long can cause a gummy residue.

This gummy residue can clog the ports and openings inside the carburetor.  The needle valve may also stick, almost as glued to the needle valve seat.

If you suspect that the leak from your carburetor has a problem with the float or float bowl, you should consult with a trained Briggs and Stratton repair technician.  Many new Briggs and Stratton carburetors require special tools to repair.

Keeping Your Briggs and Stratton Carburetor Healthy and Happy

A little preventive maintenance will keep your Briggs and Stratton engine running for many years.  Making sure the carburetor is clean is a major concern.  Never leave gas in the carburetor for more than a few weeks.  When storing your mower, run the engine until you burn all the gas out of the carburetor.

I hope that this article has given you some help in diagnosing and repairing your Briggs and Stratton engine leaking around the air cleaner.  Be careful and work safely.

Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

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