1985 Plymouth Caravelle 2.6L L4 GAS;. 1985-1988 Plymouth Caravelle 2.2L L4 GAS;. 1986-1988 Plymouth Caravelle 2.5L L4 GAS;. Gates - Driven By Possibility. Fuel Tank Cap;. Pre-Release Fuel Tank Cap;. Excess fuel system pressure is relieved through an internal spring and gasket valve that is specially designed to allow venting without losing liquid fuel.