Fuel Tank System - State Emissions Pressure Test
NUMBER: 11-63-00DATE: 11/01/00
APPLICABILITY:
1980-1989 MY SUBARU Vehicles
SUBJECT:
Pressure Testing of Fuel Tank System During State Emission Test
THIS BULLETIN IS FOR INFORMATION ONLY.
The U.S. Environmental Protection Agency has issued evaporative technical guidance requirements for conducting a functional pressure test of the evaporative system on pre-1996 model year vehicles as part of the state emission inspections. The evaporative pressure testing of the fuel tank system consists of identifying and clamping off the vapor hose line from the fuel tank as close to the evaporative canister as possible. The vehicle shall fail the test if the fuel vapor control system loses more than six inches of water pressure over a period of 120 seconds starting from a stabilized pressure of 14 +/- 1 inch of water.
Certain early model SUBARU vehicles were built with a vapor hose connecting to the evaporative canister with a small spring inserted to maintain the hose integrity while under vacuum conditions. See Figure 1 below for spring location. Under State I/M Program conditions of clamping this vapor hose, the spring prevents the clamp from creating a proper seal, which results in a false pressure test failure. SUBARU strongly recommends State I/M programs exempt the models listed in Figure 2 from the functional evaporative pressure test.
Additional Guidance
For pre-1996 SUBARU vehicles, which are deemed testable, SUBARU provides the following recommendation:
WARNING!
Improper clamping may damage the vapor hose. Clamping should only be performed using a noncutting surface grip pliers or similar tool. Ensure that the fuel tank system is pressurized in an even and consistent manner with the applied pressure not exceeding 14.5 inches of water or fuel system damage may occur. Improper pressurizing may also damage the 2-way roll over valve.
DISCLAIMER