The function of the Evaporative Control System is to prevent gasoline vapors from the fuel tank from escaping into the atmosphere. Periodic maintenance is not required only on any of the 1988-95 models (on all vehicles a sealed, maintenance-free, charcoal canister is used).
In spite of the fact that this system requires no periodic maintenance, it is a good idea to quickly look over the hoses when servicing the PCV system. If any of these hoses is cracked, torn, or rotted, the result could be vacuum leaks and consequent poor engine operation or an annoying smell of fuel vapor. If any of these hoses should require replacement, make sure to use a high quality replacement hose of a material approved for use in fuel bearing applications. Ordinary vacuum type rubber hose will not give satisfactory life or reliable performance.