Jeep Grand Cherokee

1993-1999 of release

Repair and operation of the car

Jeep Grand Cherokee
+ Cars of the Jeep Grand Cherokee brand
+ Settings and routine maintenance
+ Line six-cylinder engine
+ V8 engine
+ Procedures of the general and capital repairs of the engine
+ Cooling systems, heating and air conditioning
+ A power supply system and production of the fulfilled gases
+ System of electric equipment of the engine
- Systems of decrease in toxicity of the fulfilled gases and engine management
   General information
   System of multiposition injection of fuel (MPFI) and information sensors - the description
   Removal and installation of the electronic module of management (RSM)
   Description of the principle of action of system of self-diagnostics and procedure of reading of codes of malfunctions
   Information sensors
   System of the operated ventilation of a case (PCV)
   System of recirculation of the fulfilled gases (EGR)
   System of catching of vapors of fuel (EVAP)
   Catalytic converter
+ Manual box of gear shifting
+ Automatic transmission
+ Transfer case
+ Coupling and transmission line
+ Brake system
+ Suspension bracket and steering
+ Body
+ System of onboard electric equipment
+ Governing bodies and methods of operation

System of catching of vapors of fuel (EVAP)

General description

The EVAP system carries out adsorption of vapors of fuel and their burning as a part of gas mixture during normal functioning of the engine.

The adsorber filled with absorbent carbon in which collecting vapors of gasoline is carried out surely is a part of any system of catching of vapors of fuel. Difference of one system from another can consist in implementation management of a conclusion of evaporations. The description of the system typical for models of the brand of cars described in this manual which has to supply the owner with information sufficient for understanding of the principle of a conclusion of vapors of fuel on its car is given below.

The description given below does not apply for unambiguous compliance to the description of the system used on the concrete car, however gives an idea of the typical scheme accepted for a conclusion of vapors of fuel on the models equipped with system of injection of fuel. In spite of the fact that existence of all listed below components is obligatory in any EVAP system, on the concrete car the additional devices which are unique can be quite switched on. Be verified with VECI given a label and the scheme of laying of the vacuum hoses located under a car cowl.

The cover of a mouth of the gulf of fuel is equipped with the double-thread safety valve. The valve serves for a conclusion in the atmosphere of the evaporations which accumulated in the fuel tank in case of refusal of the EVAP system.

Other cutting (unloading) valve is installed on the fuel tank and serves for adjustment of a conclusion of vapors of fuel from a tank in a coal adsorber depending on presence at a tank of excessive or negative pressure (depending on ambient temperature).

After passing of the double-thread valve fuel evaporations on ventilating hoses come to the coal adsorber located in a motive compartment where they are adsorbed by absorbent carbon and are stored to a conclusion in engine combustion chambers.

Location of a coal adsorber of the EVAP system.

When the engine is started and warmed up to in advance established temperature the cutting electromagnetic valve of a purge near an adsorber is closed, providing opening with depression of the inlet pipeline of the diaphragm valve of management of an adsorber purge. At the same time vapors of fuel are removed from an adsorber also as a result of depression of the inlet pipeline.

The electromagnet of management of a purge of an adsorber is located on the left side of the engine, in the neighbourhood with TPS.


Full check of the EVAP system lies outside qualification of the average amateur mechanic. Fortunately the system of catching of vapors, as well as any other subsystem of system of decrease in toxicity of the fulfilled gases gets under guarantee certificates of manufacturer (5 years, or 80 000 km (50 000 miles) of a run at the time of drawing up this manual). Perhaps, the system will never fail during all service life of the car, however, anyway it is necessary to check a condition of its hoses and a coal adsorber from time to time.

Always first of all check a condition of hoses, the detachment or damage of most of which often appears an EVAP system cause of failure. For check of correctness of connection of hoses be verified with the scheme of the laying of vacuum hoses put on Schild, fixed on a radiator support under a car cowl. In case of need make repair or replacement of the damaged hoses.


  1. Disconnect a vacuum hose from the diaphragm valve of a purge of an adsorber (it is located on the inlet pipeline) and connect the vacuum gage to a hose. Start the engine and leave it working at single turns. Depression in a hose should not be!

Engine temperature at this check has to reach 75,5 °C.

  1. At the heated-up engine depression has to be absent (alarm depression from the electromagnetic valve of management of an adsorber purge).
  1. If depression is absent, pass to performing procedures of item 8.
  2. If depression takes place, disunite the electric socket of an electromagnet of management of a purge and check it for existence of power supply from the battery.
  1. Check presence of tension of the battery on an electromagnet of management of an adsorber purge.
  1. If tension takes place, replace the cutting electromagnetic valve.
  2. If there is no tension, check a condition of a plait of wires of RSM, in case of need make repair.
  3. Warm up the engine up to the normal working temperature. If originally depression on diaphragm there was no valve of management of a purge, check a depression source.
  4. If depression takes place, pass to item 11.
  5. If there is no depression, check the vacuum line going to the inlet pipeline for existence of damages or violation of passability of unions.
  6. If vacuum in an initial state depression takes place, check functioning of the cross over valve of the fuel tank in a workshop of dealer office.

Unloading valve of the fuel tank


  1. Remove the fuel tank (The head of the Power supply system and production of the fulfilled gases).
  2. The valve is put in the rubber plug through passage. Take it, having hooked on the one hand and having turned out the plug from a tank together the valve.

The unloading valve of the fuel tank is located in the fuel tank.

  1. You make installation upside-down.