What Happens When Water Gets in a Gas Tank?

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The presence of water in a vehicle’s fuel system can present several problems including the alteration of fuel to air ratio that will reduce engine power that may cause the engine to stall. If large amounts of water enters a vehicle’s fuel system, it can lead to prolonged cranking, stalling and a low engine RPM, or revolutions per minute.

If the car’s engine is exhibiting the following symptoms, there is a good chance that water in fuel system may be the cause.

  • Low mileage to fuel ratio – Gas that is contaminated with water will have the same volume. However the engine will only burn the fuel, which will result in reduced mileage.
  • Engine stalls – The combustibility of the fuel will be affected by the presence of water making it weaker. The engine may still be started up if the fuel has small amounts of water, but it may soon lead to the engine stalling.
  • Engine will not start – If the amount of water in the system is large enough, the engine may not start because fuel combustion will not occur. This can also lead to the engine becoming hydrolocked.

Even if water is not directly poured water into the gas tank, water can still enter the fuel system through poor quality fuel, condensation and a leaky fuel filter. An empty 200-gallon gas tank can contain .81 ounce of water vapor and a portion of it can potentially condense into water.