Varnished gas can be removed from a car's fuel line by using a fuel system cleaning additive. Pour the additive into the gas tank in accordance with the additive's directions and top off with new fuel. Drive the vehicle and accelerate using full throttle under standard driving conditions. If there is no improvement with the vehicle, it should be taken to a mechanic.
- Inspect the fuel system
Inspect the condition of the fuel lines and tank. Cracks in the line will allow water and condensation to enter the fuel line. Check the fuel tank for rust or cracks. If you find any cracks or rust, it is best to replace rather than clean the fuel tank and lines.
- Clean the lines
It is recommended that you use a fuel system cleaning additive to clean the lines. Follow the directions on the additive. Typically, the additive is poured into the fuel tank and then topped off with new gas.
- Test drive vehicle
Test drive the vehicle to determine if the fuel additive has made any improvement. Drive the vehicle on streets and freeways that enable you to accelerate using full throttle and standard driving conditions. If you still experience problems with the vehicle, take it to a mechanic.