Repair instructions
What Happens if There’s Water in Your Gas Tank?
Water contamination in your vehicle’s gas tank can lead to severe engine performance issues, including rough running, stalling, and potential damage to the fuel system. If left unaddressed, this problem can corrode critical fuel system components, resulting in expensive repairs. The most common signs of water contamination include the check engine light turning on, the engine running rough, and the vehicle stalling shortly after refueling.
1. What Happens if You Put Water in a Gas Tank?
While it’s unlikely that you’ll intentionally pour water into your gas tank, water contamination is still a concern—especially when refueling at certain gas stations. Water can seep into underground fuel storage tanks through condensation or seepage and end up in your car’s fuel. When this happens, the water in the gasoline can lead to serious engine performance issues, such as rough running and stalling. Over time, water contamination can corrode parts of the fuel system, leading to costly repairs.
2. Symptoms of Water in a Gas Tank
When there’s water in the gas tank, your vehicle may show several symptoms. These include:
2.1. Engine Runs Rough Shortly After Refueling
Water is not combustible, so when it enters the engine’s fuel system, it can cause misfires and rough idling shortly after refueling.
2.2. Vehicle Stalls Shortly After Refueling
If enough water enters the fuel system, your car may stall because the engine cannot combust the water in the fuel mixture.
2.3. The Check Engine Light Illuminates
Your vehicle’s engine control module (ECM) monitors for misfires or unusual engine behavior, and if it detects issues caused by water contamination, it will trigger the check engine light. The ECM may also store a diagnostic trouble code related to water contamination.
3. How Much Water in a Gas Tank is Bad?
Even small amounts of water in the fuel can cause issues. If the contamination is minimal, you may be able to address it by using a fuel additive like dry gas (isopropyl alcohol), which helps break up the water and restore the fuel’s combustibility. However, larger amounts of water will likely require draining the fuel tank and cleaning the fuel system. Continuing to drive with water-contaminated fuel can lead to significant damage to components like the fuel injectors and pump.
4. How to Check for Water in Your Gas Tank
Water and gasoline have different densities, so they will naturally separate when mixed. Gasoline weighs about six pounds per gallon, while water weighs about seven pounds per gallon. You can check for contamination by taking a small sample of fuel and placing it in a clear container. If the sample separates into two layers, the bottom layer is likely water.
There are also commercial test kits available that can confirm whether your gasoline has been contaminated with water.
5. How to Protect Your Vehicle from Water-Contaminated Gasoline
To minimize the risk of water contamination, consider the following tips:
- Choose high-traffic gas stations: These stations typically have fresher fuel with a higher turnover rate, reducing the likelihood of water contamination.
- Avoid refueling during tanker deliveries: Gasoline deliveries often stir up water and debris that may be settled in the underground tanks.
- Always keep your receipt: In case you encounter water-contaminated fuel, having a receipt gives you a record of where you purchased the gasoline, making it easier to resolve the issue with the station.
If you suspect water contamination in your fuel system, it’s best to consult a professional mechanic immediately. Addressing the issue quickly can save you from costly repairs and prevent further damage to your engine and fuel system.
