Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Alcohol/Contaminants-In-Fuel Diagnosis: Notes
The concentration of alcohol-in-fuel can be detrimental to the fuel system. Higher than recommended alcohol-in-fuel concentrations may cause driveability problems such as hesitation, lack of power, stall, no start, etc. High concentrations may also cause corrosion of the fuel system components and subsequent fuel filter plugging as well as deterioration of the rubber and the plastic components. Commercial automotive fuel can contain alcohol in various types and levels of concentration. Some forms of alcohol are more detrimental to the fuel system components than others. If an excessive amount of alcohol-in-fuel is suspected as the cause of a driveability problem, the following procedure can be used to detect its presence. This procedure uses water to extract the alcohol from the fuel. The specific type of alcohol contamination cannot be determined from this test.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.