Water in Fuel System

If water enters the fuel system, it can alter the fuel/air ratio and reduce engine power and/or fuel economy, potentially stalling the engine. If water enters the combustion chamber in small amounts, it may be evaporated from the engine heat. If the amount of water is significant, the water can soak the spark plugs and cause an electrical short to the block or making for a weak spark. Enough water can cool the engine to a point where the water cannot boil away. This could cause extended cranking, stalling, or stumbling/very low engine RPM (around 300-500 RPM).

Table of Contents

• 1. Symptoms
  • 1.1 Poor Fuel Economy
  • 1.2 Poor Quality Fuel

Symptoms

Poor Fuel Economy

Condensation can gather in your fuel tank naturally from the different temperatures and the mixture of fuel and air inside. If the condensation is left unattended it can pool enough water to get inside the fuel system and effect fuel economy. Since water does not burn the engine will have to work harder on watered down fuel, this will rob performance and fuel economy. This can be remedied by pouring a fuel stabilizer or "dry gas" in your fuel tank at every oil change or regular service. This is also recommended in colder climates aswell because if enough water is in the fuel tank it can freeze around the fuel pump and prevent it from starting.

Poor Quality Fuel

Old or mismanaged gas stations can sometimes get too much water condensation inside their fuel reserve tanks, this fuel is then pumped into your vehicle and in some cases will cause a check engine light to come on and perhaps cause misfires and damage to the catalytic converter from too many contaminants in the fuel or too much water.