Is Driving Without Gas Cap Dangerous?

A gas cap is a cover that fits onto your car’s fuel system that prevents fuel and fumes from leaving the tank. Although it isn’t dangerous to drive a vehicle without a gas cap, it could lower your fuel efficiency and cause damage to both the environment and your engine.

Is Driving Without Gas Cap Dangerous

Is It Safe To Drive Without A Gas Cap?

As mentioned above, driving a vehicle without a gas cap isn’t seen as dangerous, and nor does it come recommended. In other words, it is not safe for the environment or the long-term health of your vehicle.

Do You Need A Gas Cap To Drive?

A car without a gas cap won’t pass a routine car inspection in certain countries and states. Why? It will likely trigger an engine light, which is a big enough reason to fail.

What Problems Can A Loose/Lost Gas Cap Cause?

A loose or a lost gas cap can enable unwanted contaminants to enter your car’s fuel tank through “cold running.”

When this procedure occurs, both the moisture and dirt from the gasoline’s evaporation could eventually cause the engine to misfire.

We’ve listed a handful of other issues a lost or missing gas cap can cause below.

Losing fuel economy

If your gas cap has been misplaced or is loose, you may lose fuel economy. The evaporative emission control setup could become impaired. This often occurs when fuel that hasn’t yet been burned escapes from you’re car’s filler neck. This unburned fuel is then released into the atmosphere, which can cause a great deal of harm to the environment.

It can also enable moisture and dirt to enter your vehicle’s fuel set-up. As mentioned above, this is referred to as ‘cold running.’ This term equates to performance issues, including lower power and a lesser-powered control platform.

This can cause pricy components to become damaged due to increased temperatures and fuel wastage.

Engine misfires

A loose gas cap can readily invite contaminants into your car’s fuel tank. This unwanted moisture and dirt cause engines to misfire, which often means a high bang when out on the road.

This dirty moisture and debris can also cause stalling and idling, harming your ignition system. Some contemporary cars will warn you of this with a fuel cap light on the dashboard.

Environmental issues

When you allow unburned fuel to evaporate into the outside air, it doesn’t disappear; these fuel vapors become pollution and negatively affect the environment.

Those gas tank hydrocarbons will be poured into the environment, negatively affecting the outside air we breathe in daily.

You’ll pay higher fees for gas

Cruising around without a gas cap or even a loose gas cap can cost more when fueling up. This is down to gas leaks, which equate to lost fuel. On average, a loose or missing gas cap may add 11 cents to your gasoline costs per gallon.

The vehicle’s under-car gas tank system of vapor recovery

When a vehicle’s gas cap is missing or loose, the recovery system for the under-vehicle gas tank vapor can lose its vacuum, which means vapors are burnt off. This is known as flaring and prevents vapors from being recycled back into your car’s engine.

These leaked fuel vapors can cause a safety issue to those standing around your car, such as pedestrians.

Is Driving Without Gas Cap Dangerous

How Long Can You Drive Without A Gas Cap?

This is dependent on your vehicle, especially its age of it. Many modern cars boast technology that forces the vehicle into what is known as limp mode – when the gas cap or fuel cap hasn’t been replaced.

This means the vehicle will be given limited power output, often meaning you won’t be able to drive over a speed of 20-30 mph. This won’t work for many, especially not on a motorway.

If this is happening and your check engine light is on, it is likely your fuel cap has been misplaced, or you have a failing gas cap. You will need to find a replacement gas cap as quickly as possible to render the situation.

Is It Illegal To Drive Without A Gas Cap?

A car with no gas or fuel cap will fail an inspection in certain states. On top of being illegal, numerous contemporary vehicles won’t allow you to drive with no cap in place as an alarm or engine light will be triggered.

Again, this check engine light could be a reason for failing a motor check or inspection.

Temporary Gas Cap Alternatives

If you require a temporary gas cap, you can create a nifty fuel cap using household items such as plastic caps, aluminum foil, plastic bags, or cork.

However, these are only temporary measures and shouldn’t be used as a permanent fixtures for gas caps.

Gas Cap Replacement Cost

In most cases, however, this does depend on the make and model of your vehicle, the cost of a gas cap on average falls under $99. Parts for gas caps cost around $76, while labor costs, on average, are about $18 and $22 per hour.

These figures don’t include additional fees, such as taxes for fuel caps.

Where To Buy A Gas Cap

If your check engine light has appeared, it is likely your car’s gas cap has failed, or you simply may be driving without one, having left the gas station in a hurry.

You can purchase a replacement gas cap or fuel caps from a wide range of garages, professional mechanics, and online. When investing in a new gas cap, purchase the correct version for your exact vehicle.

If you are unsure, you can visit an auto parts store, or you search the database from retailers like AutoZone.

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Author: Dave Johnston

Dave Junior is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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