All 4.0L engines from 1987-98 and all other engines from 1991-98 employ a Multi-Port Fuel Injection (MFI) system. The MFI system injects fuel into the intake manifold above the intake valve port of each cylinder through separate injectors.
The fuel system consists of the fuel tank, electric fuel pump, fuel filter, fuel tubes, fuel hoses, vacuum hoses, throttle body, and the fuel injectors.
A fuel return system is used on all vehicles. The system consists of the fuel tubes and hoses that route fuel back to the fuel tank, except on 1996-98 models. Jeep vehicles for 1996-98 do not utilize a separate fuel return line from the engine to the tank; instead, fuel is returned through the fuel pump module and back into the tank through the fuel pressure regulator (1996) or fuel filter/pressure regulator (1997-98).
The fuel tank assembly consists of the tank, fuel gauge sending unit/fuel pump assembly, filler vent tube, rollover valve and a pressure filler cap (on some models).
Another part of the fuel system is the evaporation control system, which is designed to reduce the emission of fuel vapors into the atmosphere. The description and function of the evaporative control system is found in Emission Controls .