Gas Leaking From Bottom Of Car – Causes, Symptoms, and Fixes

A gas leak is one of the easiest leaks to identify in a car. You don’t need to wait until you see puddles underneath the vehicle or anywhere around the gas system. If you perceive gas around your car, you likely have a gas leak.

A burning mixture of gas and air releases the energy needed to power the vehicle and move the wheels. A gas leak happens when there’s an escape of fuel from a damaged fuel delivery system. This situation may seem like a minor case, but it is quite dangerous. Gasoline is a highly flammable substance.

Gasoline can leak from anywhere within the fuel delivery system components. However, this article will focus on the reasons behind gas leaking from the bottom of a car. We’ll also look at gas leak symptoms in a car and how to fix car leaking fuel.

car leaking fuel

Symptoms of a Gas leak in a car

Automakers design fuel tanks to withstand extreme weather conditions, harsh road conditions, and pressures. This, however, doesn’t mean it’ll last the life of the car. Instead, like several vehicle components, it’ll develop a fault over time and leak gasoline.

Several factors can cause a gas leak. There are several gas leaks in car symptoms you should watch out for.

Sweet/gasoline smell

Gasoline fuel emits a slight sweet smell. However, many motorists may not describe this as a sweet smell. It all depends on how you describe the gasoline smell. United states agency for toxic substance and diseases registry (ATSDR) reports that gasoline contains benzene, responsible for its distinct smell. The benzene helps to provide better gas mileage and boosts overall vehicle performance.

You can perceive a gas smell when idling your car or cruising down the road. The combustion chamber should quickly burn the gasoline, or it disappears through evaporation.

If the smell lingers for an extended period or gets stronger, you have a fuel leak or a gas vapor escaping into the ambient air. Therefore, watch out for other symptoms of a car leaking gas when parked or driving.

Large fuel gauge drop

A common sign of a gas leak in your car is a large fuel gauge drop. However, this is not for dummies because, naturally, your vehicle should lose gas as you drive.

Therefore, the vehicle needs to lose an excessive amount of fuel for you to notice. This can happen both when driving and when parked. If a leaking gas is a culprit, a gasoline smell will accompany it.

Gasoline puddles underneath your car

Another obvious sign of a gas leak is fuel puddles underneath a vehicle. Gasoline differs from your engine oil and other car fluids. It dries off faster than water. So, the puddles will not be much unless the leak is severe, which can easily lead to explosions.

If you suspect a gas leak, look underneath the car for puddles. You should smell the puddles if you notice them. If it’s a gas leak, you’ll perceive its distinct smell.

Why Is Gas Leaking From The Bottom Of My Car?

A few parameters could cause gas to leak from the bottom of the car. Now that you’ve known the symptoms of a gas leak let’s, look at where you should inspect once you observe a gas leak.

my car is leaking gas and wont start

Leaking fuel hoses and lines

The fuel pump transports gas from the gas tank to the injectors via the gas lines. If these hoses have mechanical impacts, are rusted, or are worn, they’ll leak gas. Of course, gas leaks are very dangerous. Loose gas lines or improperly fitted hoses can leak gas from the bottom of a car.

Excessive vibrations

Driving rough on rough terrains is not good. It will cause jostling and vibration on several system components, which could knock lose some fuel system components. This is pretty rare in new vehicles but is common in older cars.

The vibration is not always the cause. However, it could mean your mechanic did not properly fix or tighten the fuel components.

Lousy Rubber seals or O-rings

The O-rings are those round rubber seals fitted on the injectors to prevent oil or any unwanted substance from entering the combustion chamber. It also prevents gas leaks from the injectors.

It sits on the cylinder head; therefore, it is exposed to heat. Over time, the seal will become brittle and cause a gas leak. Gas leaks from this region are very dangerous as they cause explosions in a few minutes.

Here’s why; gas leaks from the O-rings will drop underneath the vehicle. While dripping down on the floor, it could drop on a hot exhaust pipe. Of course, you know what this means. It will cause an explosion in a few seconds or minutes.

Leaking fuel tank

As the name suggests, fuel tanks store all the gas in a vehicle. When refueling your car at a gas station, the fuel goes directly to the gas tank. If the gas tank is damaged or leaks, it’ll project a catastrophe to the fuel system and compromise the safety of the vehicle. A leaking gas tank is one of the primary causes of gas leaks from the bottom of a car.

Faulty gas cap

The gas cap prevents fuel fumes from escaping into the air, keeps the gas from leaking, and maintains adequate fuel pressure. If the cap becomes faulty, it can cause gas leaks. The gas will not leak in most cases, but the fuel fumes will escape.

How To Fix Gas Leaking From The Bottom Of My Car

Since there are several causes of gas leaks from the bottom of a car, there are many ways to fix it. Fixing a gas leak from the bottom of a car requires tracking where the leak is coming from and repairing or replacing the culprit.

For instance, check the O-rings on the injectors. Replace them if they are the cause. Second, check and replace the gas cap if it is defective. Third, examine the fuel line around the leaking regions and replace it if needed.

Of course, a damaged fuel tank is another culprit you should not ignore. First, inspect the fuel tank and see if it is where the fuel is leaking from. If a defective gas tank is a cause, you can easily fix it with the below guide.

There are two methods to fix gas tank leaks. We’ll explain the methods based on the severity of the gas leaks. But, first, here is how to stop small gas leaks from the fuel tank.

Small gas tank leaks

Items needed

  • Sandpaper
  • Small brushes
  • Gas tank repair kit
  • Jacks
  • Jack stands
  • Gloves
  • Safety glasses
  • Filtration masks
  • Clean rag or towel
  • Vinegar

Step 1: Lift the vehicle

Lift the car and support it with Jack’s stands. Don’t bother taking off the tires. The purpose of lifting the vehicle is to easily gain access to carry out the repair task.

Lower the vehicle the moment you support it with jack stands so that the car won’t rely on the jack alone. You can also lift the vehicle with a four-post or two-post car lift.

Step 2: Determine where the gas is leaking from

Place your mechanic laying board underneath the vehicle. Slide under and determine where the leak is coming from. You can also look for a small hole in the leaking area.

Step 3: Brush or sand the leaking regions

Brush the dirt and grime on the leaking surfaces. You can use a metal brush or sandpaper. But, first, brush all the leaking surfaces.

If you could not determine the leaking spot earlier on, brushing the surface will make it easier.

Step 4: Clean the brushed areas and drain the gas

Dip the clean rag or towel into the vinegar and clean the brushed areas. Ensure you clean the surface properly. Watch out for any dirt, grease, oil, or particles that’ll prevent the gas tank repair kit from holding when you apply it.

Re-clean the brushed areas again and keep them sparkling clean. Finally, you can remove the gas in the tank to allow the repair kit to work pretty fine.

Step 5: Apply the gas tank repair kit

Apply the gas tank repair kit to the leaking areas. Read the instructions on the repair kit to know how to apply it. Ensure you follow the instructions on the repair kit so that the leak will stop.

Step 6: Refuel the gas tank

Allow the repair kit to do its magic. Once the applied repair kit is dried up, refuel the gas tank. Allow the gas to sit for 2-3 minutes.

Next, check if the leak is still there. If you followed the instructions here, the gas leak should stop by now and prevent the leak for some years.

Large gas tank leak

However, if you have a large gas leak, ‌follow another approach. The repair kit will not work properly on large gas leaks.

Here’s what you need to do for a large gas leak on the gas tank.

  • Lift the vehicle and support it
  • Locate and loosen the mounting bolts
  • Disconnect the hose and electrical connections
  • Gently lower the gas tank
  • Remove the gas tank from underneath the vehicle
  • Drain the fuel
  • Clean the gas tank with water and detergent
  • Add some solvent and let it sit for 15 to 30 minutes
  • Rewash the tank and allow it to dry
  • Weld the leaking areas
  • Reinstall the fuel tank following the reverse process.


Q: How serious is a gas line leak?

Gasoline is a highly flammable liquid. Hence, a gas leak is very dangerous and can cause an explosion. If you suspect a gas leak in your vehicle, inspect and fix it before hitting the road.

If you can’t fix it at home, call your mechanic to tow it to his workshop. No matter the severity of a gas leak in your car, do not ignore it for any reason.

Q: Can I drive a car with a gas leak?

No. gasoline is extremely flammable, and it’s the cause of fire explosions in a vehicle. For this reason, do not drive with a gas leak.

Whether the leak is coming from the fuel tank, fuel lines, or O-rings, it can cause an explosion. So, whenever you determine a gas leak, contact your mechanic to fix it before hitting the road.

Q: How much does it cost to fix a gas line leak in a car?

A gas leak in a car can cause catastrophic damages when you least expect it. So, what’s the car gas leak repair cost to budget to fix the gas line leak?

The average cost of repairing a gas line leak is around $85. This price varies from vehicle to vehicle. Other parameters that affect the gas line leak repair cost are the location of the leak in the car, your location, and the mechanic handling the repair.

Depending on the parameters above, you can spend as little as $50 or as high as $150 to fix a gas line leak in a car.

Q: How much does it cost to fix a leaking gas tank?

Fixing a leaking gas tank leak is more expensive than a gas line repair.

Depending on the cause of the gas tank leak, you’ll spend as little as $150 or as high as $550. There are two causes of gas tank leaks. First, it can be a result of corrosion or punctured impacts.

A corroded fuel tank requires an easy fix option. You can fix it by applying a gas tank repair kit to the leaking surface.

Q: Where does gas leak from a car?

Gasoline can leak from anywhere on the fuel delivery component. For example, gas leakages can come from dried-up O-rings, worn-out, or punctured gas lines or hoses.

Of course, fuel can also leak from faulty gas caps and corroded or punctured fuel tanks.

Q: Can you patch a leaking gas tank?

There are two or more methods to fix a leaking gas tank. A suitable method depends on how big or small the leakage is.

If you have a small leak, the best method is to get underneath the vehicle and patch it with a gas tank repair kit. You may wonder how long it takes to fix a gas leak in a car. You can fix a gas leak in a car within one to two hours.

Q: Can a hole in a gas tank be repaired?

A punctured hole in a gas tank can be fixed no matter how big it is. Here are the steps to repair a hole in a gas tank;

  • Uninstall the gas tank
  • Remove the gas inside
  • Wash the tank and allow it to dry
  • Weld the punctured areas
  • Reinstall the tank following the reverse process.

Q: Is it safe to drive a car that smells like gas?

Can you drive with leaking gas? Yes. Is it safe to drive with it? No.

A gas smell may be a minor case. But it lingers for an extended period, don’t drive with it. It is very dangerous to do so.

Final Words

Gas leaking from the bottom of a car is dangerous. Therefore, fix it immediately to prevent a catastrophic explosion. Once you perceive a gas smell from your car, taking the measures will reduce the repair bills and save you time and your life.

This article has explained the symptoms of a gas leak in a car, its causes, and how to fix it. Now, you can easily identify a gas leak and fix it as soon as possible.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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