DESCRIPTION
The fuel evaporation system is designed to prevent fuel vapor from reaching atmosphere. System includes a plastic fuel tank, vacuum relief filler cap, roll-over valve, check valve, charcoal canister, and connecting lines and hoses.
OPERATION
When engine is stopped, fuel vapor from fuel tank flows through vapor line into charcoal canister where it is stored. When engine is running, fresh air is drawn through charcoal canister as manifold vacuum pulls the stored fuel vapor into the combustion chambers for burning. The check valve regulates the amount of vapor flow.
A roll-over valve in the fuel evaporation line shuts off line if vehicle turns over. It is located in-line, above fuel tank.
The special fuel filler cap contains a vacuum relief valve to let air into the tank if the vent lines become plugged. This prevents tank collapse or engine fuel starvation.
EVAPORATION SYSTEM PRESSURE TEST
| CAUTION | Use adequate ventilation and do not smoke when pressure testing fuel evaporation system. |
- Remove vent hose leading to fuel tank from charcoal canister. Using a "T" fitting, connect Saab APC Boost Pressure Gauge (83-93-514) and hand pump type coolant pressure tester to fuel tank vent hose. NOTE: Damage to fuel pump and mount, and tank grommets may occur if system is pressurized above 3 psi (.21 kg/cm 2 ).
- Slowly pump air into hose until pressure reaches 3 psi (.21 kg/cm 2 ) maximum. Maintain 3 psi (.21 kg/cm 2 ) maximum on system for at least 5 minutes.
- Using a soap water solution or HC meter, test for leakage at fuel filler cap and neck, fuel pump, hoses, connections, tank grommets, and fuel level sending unit.
- Tighten or replace any leaking component and retest. If new tank grommets leak during retest, seal them with Saab Special Sealant (30-21-250).
MAINTENANCE
Check system at 60,000 miles or 4 years, and every year thereafter. Replace charcoal canister at 60,000 miles. Inspect all hoses and components for damage, leaks, and deterioration.