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ATV Oil Smells Like Gas

The only time you want to smell raw gas is when you’re handling gas. So if you smell it at other times, you’re going to take notice. Things get particularly weird when you notice your ATV oil smells like gas. This post will tell you why you have a gas smell in ATV oil and how to fix it.

atv engine oil check

Why You Need to Fix a Gas Smell in ATV Oil Right Away

There are several reasons your ATV oil dipstick smells like gas.

First, your oil is diluted and not working properly so your engine is probably getting too hot or dry.

Gas in the cylinder degrades its oil coating, which can lead to engine damage or failure.

Rich-running engines also build up contaminants in the cylinder head. This can cause engine overheating, pre-ignition problems, and burning valves and seats.

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Carburetor Leak

When your ATV motor oil smells like gas, check your carburetor first. Your carburetor regulates the mixture of air and gas. It makes sure the air to gas ratio is ideal, even under various engine loads, and it makes sure there is enough gas in the fuel bowl. The fuel bowl is a part of the carburetor that holds gas in reserve for quick use. A float, float needle, and a seat for the needle determine how much gas is in the bowl.

Float needle

Every float needle and seat will eventually get old and damaged and begin to leak. As it lets excess gas enter the fuel bowl, the gas will begin to enter the cylinder and the crankcase. You may notice a gas smell in ATV engine oil, an excessive oil level, and maybe even gas in your air box. When gas makes it into your cylinder, it can inhibit the motion of the piston.

This is the most common reason for someone to have a fuel smell in ATV oil. You can determine if the needle and seat are leaking by removing the fuel bowl and leaving the fuel line attached. Gas will be flowing. If you lift the float, you should see that the gas stops moving. If it doesn’t, your needle and seat need to be replaced. You can replace them separately, but it’s better to replace both at the same time because if one went, the other is likely to follow.


If your needle and seat passed the test, then your fuel float may be why your ATV engine oil smells like gas. The float may be worn or simply poorly aligned.

If it’s an alignment issue, you can fix it. It will require that you learn the specifications for your float and tinker with it to make sure you have it where it stops the gas flow.

If the float is worn, you have to replace it.

Faulty Petcock

Your petcock can also allow fuel to get into your oil. There are two types of petcocks that people are likely to have, a manual type and a vacuum-operated type.

Vacuum-operated petcocks have a rubber diaphragm and vacuum line so that when the engine cranks, a vacuum forms in the line and opens the diaphragm to let gas in. When this diaphragm gets old, gas leaks into the combustion chamber. You’ll experience signs that your engine is running rich like black smoke, backfiring, bogging, and misfiring. You can prove this is the problem by removing the vacuum line and checking it for gas. You’ll also find your ATV oil smells like fuel.

You can use a sealing agent to repair the diaphragm, replace the diaphragm, or buy a new petcock.

What To Do After Your ATV Oil Smells Like Gas

No matter which problem made you have to Google, “my ATV oil smells like gas,” or how you fixed it, you need to follow up any repair involving a gas smell in your oil by changing the oil, the oil filter, spark plugs, and the air filter.

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