Fuel tank cap: common defects and their signs.

1. Breakdown of cap valve.
   • “Check Engine” indicator lights up on the dashboard.
   • Specific hissing sound occurs at tank opening.
   • Fuel stains  are noticeable from the cap side.
   • Engine power decreases after its warming-up.
2. Mechanical damages.
   • Noise appears at engine warming-up.
   • It is impossible to close the cap tightly.
   • Fuel consumption increases.
   • Detonation of the engine may occur.

How to replace fuel tank cap?

Specialists recommend to perform scheduled inspection of the car fuel tank cap every year. The component is not repairable; it should be replaced at appearance of defect signs. Buying a new car fuel tank cap, make sure that its diameter, quantity of valves, and type and pitch of the thread are the same as the corresponding characteristics of the defective part.

Replacement procedure depends on production material and the type of the fuel tank cap. The components are classified by the mounting and ventilation types. Component replacement can be performed by yourself if you have a standard tools set and car servicing experience. Before starting works, check out vehicle technical documentation, as the sequence of steps may vary for different car models. Basically, you need to follow the below-stated recommendations to replace the component:

1. Unscrew elements fastening the cap to the car body.
2. Disconnect a holder of the cap and remove it.
3. Install a new component, reassemble in the reversed order.

After installation of a new component, make sure that it provides required tightness of the fuel tank.