Evaporative Loss Control Pressure Test (1991 & Later)

The following procedure provides a method for checking system if a leak is suspected. Excessive leakage will affect evaporative loss control:

1. Ensure at least two gallons of fuel in tank.
2. Disconnect, at adsorption canister, pipe to vapor separator.
3. Connect this pipe to nitrogen cylinder and water manometer using "T" piece.
4. Pressurize system to 26.5 and 27.5 inches of water, allow reading to stabilize, turn off nitrogen supply.
5. Measure pressure drop, if drop exceeds 2.5 inches of water after 2 min 30 sees, a leak is indicated. Note that a fully sealed system will show a slight pressure increase.
6. If system leaks, maintain pressure, and apply soap solution round all connections until bubbles reveal source of leak.
7. Repair leak.
8. Repeat test. Remove test equipment, if successful.
9. Reconnect pipe to adsorption canister.