Why did methanol create problems in some automobile fuel systems?

Methanol creates significant challenges in automobile fuel systems primarily due to its properties as a polar organic solvent. Because of this solvent nature, methanol tends to dissolve the plastic and rubber components commonly used in modern fuel systems, particularly in fuel-injected vehicles.1

These chemical interactions can cause these components to crack or dissolve over time when exposed to the fuel. Consequently, for a vehicle to utilize methanol as a fuel source, manufacturers must employ specialized materials capable of withstanding long-term exposure to the compound without degrading. These compatibility issues, alongside the growing preference for ethanol-based fuels, have contributed to the reduced commercial interest in methanol as a standard motor fuel.1