How to Tell if Someone Put Something in your Gas Tank

How to Tell if Someone Put Something in your Gas Tank

How to tell if someone put something in your gas tank can take time before you notice but lead to many engine problems and expensive repairs.

Bad tank breathing or leaks are common causes of water and other substances getting into the combustion system.

Of course, your car can’t run on water, and if something blocks fuel flow, it will stall. In this article, you will find out how to tell if someone put something in the gas tank.

You will also learn about common symptoms of water in the fuel filter.

How to Tell if Someone Put Something in your Gas Tank

1. Slow acceleration

When the injectors spray the right amount of fuel into the combustion chamber and combine it with air, the engine runs at optimal power.

This means you will notice your car’s speed increase based on how hard you press the fuel pedal.

But again, if something like water enters the combustion system, it interferes with the engine sensors, causing faulty readings.

The engine runs too rich or lean, affecting the normal air/fuel mixture. As a result, engine power reduces, causing low acceleration. 

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2. Rough acceleration

Rough acceleration is another common sign of water or something in the gas tank. When water combines with the fuel, poor air/fuel mixture occurs in the combustion chamber.

The engine then compresses the water, causing noticeable power loss. The car will often sputter and surge forwards as you drive once the engine receives clean fuel.

3. Shaking/ rough idle

Rough idling is an easy-to-note symptom if water gets in the gas tank. The car will shake, and the RPM will change unannounced.

When the water gets in the engine, it will cause misfires. It may also clog fuel injectors and lead to faults such as broken pintle, disc, or return spring.  

4. Steam from the exhaust

When water gets into the exhaust pipe or combustion chamber, it vaporizes. This causes wispy white steam to appear from the tailpipe.

The white smoke can result from a faulty Engine Control Unit (ECU), cracked cylinder heads, or a damaged coolant reservoir.

Also, it could be a problem with oil leaks or the fuel injector. Don’t confuse the wispy steam with the slight smoke a car produces after igniting in the morning.

Also, note that blue or gray smoke will signify leaking valves or seized piston rings, while black smoke will be a sign of raw fuel burning due to a faulty fuel pressure regulator or engine sensor.

Read: If a car is submerged in water is it totaled?

5. Rust and water drips

Rust is often a significant problem in vehicles equipped with steel tanks. When water gets in and combines with gas, rust occurs and corrodes the tank’s walls. Leaving the corrosion for a long time will develop leaks.

You will notice drips of fuel/water mixture under the fuel tank after parking the car for some time.

Your best shot to solve this problem is to replace the tank as soon as possible. Be sure to check the fuel filter and replace it if necessary since it may also have rust.

6. Engine light on

The beauty of most modern cars is their full-time computerized monitoring engine sensors.

If something alters the normal functionality of the engine, the sensors send fault values to the dashboard control unit. This results in the generation of trouble codes that cause the engine light to flash.

But again, the engine light can blink because of other problems such as vacuum leaks or overheating. You can use an OBD2 scanner to confirm the issue instead of assuming it is a fuel-water mixture problem.

7. Hard start

You can tell whether your car has a water problem based on how it starts. If the ignition is faulty, the cranking time increases. This can result from different reasons.

A top cause is if the spark plugs fail to get enough fuel, which signifies that something is standing on the fuel way. Another cause is if the air/fuel mixture is incorrect.

Sometimes, the engine cannot start if it has so much water. It often becomes hydro-locked as the pistons try to compress the water. This leads to damages to the internal components such as the crankshaft bearings.

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Frequently Asked Questions on Diagnosing your Gas Tank

How do you get water out of the gas tank?

The best way to fix the problem is to empty the tank. You can use a vacuum machine to suck out the water. Afterward, replace the fuel filter and refill the tank with clean fuel.

Do I need to empty the entire tank to solve the water problem in the gasoline?

No, if the amount of water is small, you can refill the tank with high-quality fuel and drive as usual. You can also add an additive like Hydroburn G or Iso-HEET to solve the problem.

Does water affect fuel efficiency?

Yes, if water combines with air/fuel mixture in the combustion chamber, the engine’s power output reduces. The ECU injects more gas to maintain the car’s performance, leading to negative fuel economy.

What causes water to get into the gas tank?

A broken or loose fuel cap can let water droplets into the tank when washing the car or when it rains. Also, a worn-out fuel pump can accumulate moisture into the tank.

How do you know if the fuel tank cap is letting in water?

An intact cap depressurizes the tank and produces a hissing sound when you open it. If yours doesn’t, it may be loose and needs a replacement.

Can fuel at the pump be contaminated with water?

Yes, the fuel can get contaminants and water along its channel to the pump despite being distilled in the refinery. The storage pump at the refilling station can also have leaks, which will transfer contaminants to your car when you fuel. 

Now that you know how to tell if someone put something in your gas tank, some of the mentioned problems can result from phase separation.

This happens when gas that contains ethanal surpasses its shelf life in your car—two or more months. In this case, gasoline separates from water and floats in the tank.

When you try to ignite, the fuel pump will pump a mixture of water and fuel. It is wise you consult a mechanic to help you fix the problem since the water may have damaged several components.

Read: AC compressor noise at idle

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