Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Evaporative Emission Controls

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OPERATION



See Figure 1

The Evaporative Emission Control System (EECS) limits the amount of fuel vapors allowed to escape into the air. When the engine is not running, fuel vapors from the sealed fuel tank flow through the single vapor line to the charcoal canister mounted against the inner wheel well, in the right front of the engine compartment on 1991-97 models, or on top of the fuel tank on 1998 models. The charcoal absorbs the fuel vapors and retains them until they are purged with fresh air.

Any time the ignition switch is ON , the canister purge solenoid valve is supplied with 12 volts. Under the appropriate engine operating conditions, the PCM completes the circuit to ground, opening the valve. With the valve open, intake manifold vacuum is applied to the canister drawing in fresh air and purging the vapors. The purged vapors are then drawn into the engine and burned efficiently during the normal combustion process.

The purge valve is opened when the coolant temperature is above 158°F (70°C), vehicle speed is greater than 1 mph and throttle position is more than 4 percent open.



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Fig. Fig. 1: The evaporative emission control system

COMPONENT TESTING



Carefully check for cracks or leaks in the vacuum lines or in the canister itself. The lines and fittings can be reached without removing the canister. Cracks or leaks in the system may cause poor idle, stalling, poor driveability, fuel loss or a fuel vapor odor.

Vapor odor and fuel loss may also be caused by: fuel leaking from the lines, tank or injectors, loose, disconnected or kinked lines, or an improperly seated air cleaner and gasket.

If the system passes the visual inspection and a problem is still suspected, proceed as follows:

  1. With the ignition switch in the OFF position, unplug the electrical connector from the canister purge solenoid. Use an ohmmeter to check the solenoid coil resistance; it should be 19-31 ohms.
  2.  
  3. Turn the ignition switch ON then, disconnect the vacuum line from the intake manifold and connect a hand vacuum pump to the valve.
  4.  
  5. Apply a vacuum of about 10 in. Hg (34 kPa) to the hose and solenoid, then observe if the valve holds the vacuum. If the valve does not hold, apply vacuum directly to the solenoid to determine if the solenoid or hose is at fault, then replace the component which allowed vacuum to release.
  6.  
  7. If the vacuum holds in the initial test, jumper the test terminals on the ALDL (terminals A and B are the test terminals and are the two uppermost right terminals of the ALDL connector), and observe if the valve activates, releasing the vacuum. If the valve does not activate and release the vacuum, replace the solenoid.
  8.  

REMOVAL & INSTALLATION



Canister Purge Solenoid Valve

See Figure 2

The purge solenoid valve is mounted on the engine, towards the rear and below the intake manifold.

  1. As an added safety precaution, you may wish to disable the air bag(s), if equipped. refer to Chassis Electrical for the air bag disabling procedure.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the air cleaner/intake tube assembly.
  6.  

For DOHC engines, the solenoid can be reached through the access hole located next to the intake manifold support bracket.

  1. Unplug the solenoid vacuum hoses and electrical connector.
  2.  
  3. Remove the attaching bolt, then remove the canister purge solenoid.
  4.  

To install:
  1. Install the solenoid and tighten the retaining bolt to 19 ft. lbs. (25 Nm).
  2.  
  3. Connect the vacuum lines to the solenoid, then install and push in the electrical connector until it clicks firmly into place.
  4.  
  5. Install the air cleaner/intake tube assembly.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. If necessary, enable the air bag(s). refer to Chassis Electrical .
  10.  



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Fig. Fig. 2: The canister purge solenoid is mounted below the intake manifold

Charcoal Canister
1991-97 MODELS

See Figures 3, 4, 5 and 6

  1. Raise the front of vehicle sufficiently for underhood and undervehicle service, then support safely using jackstands.
  2.  
  3. Remove the right front tire from the vehicle.
  4.  
  5. Remove the right inner fender well. The fasteners at the front corner should be carefully pried free using a small prybar.
  6.  
  7. Disconnect the vacuum hoses from the canister.
  8.  
  9. Remove the bracket assembly fasteners or the band clamp fasteners, as necessary, then remove the canister from the vehicle.
  10.  

To install:
  1. Install the canister into the bracket assembly with the ports correctly positioned, but do not tighten the bracket fasteners until the vapor lines are installed.
  2.  
  3. Connect the vacuum hoses to the top of the canister, making sure that no lines are kinked or damaged. Tighten the canister/bracket assembly fasteners to 22 ft. lbs. (30 Nm). The canister air inlet is routed into the vehicle frame rail on 1991 vehicles while 1992-97 vehicles are equipped with a special air inlet cap.
  4.  

Be careful not to overtighten the assembly fasteners or the charcoal canister may be damaged.

  1. Install the inner fender well and the right front tire.
  2.  
  3. Remove the jackstands and carefully lower the vehicle.
  4.  



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Fig. Fig. 3: Lift out center of plastic fastener with a small bladed screwdriver



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Fig. Fig. 4: Pull out the fastener from the inner fender splash shield



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Fig. Fig. 5: Location of the evaporative canister at the right front of the engine compartment-1991-97 models



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Fig. Fig. 6: Installation and vapor hose routing for the charcoal canister

1998 MODELS

Saturn models for 1998 have the evaporative charcoal canister mounted on top of the fuel tank assembly. The fuel tank must be removed to access the charcoal canister. For fuel tank removal procedures, refer to Fuel System .

 
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