Hi - My car has always blown low numbers and passed smog. Its last test was in 2009. Is there anything new with the evap test that is stricter in 2011? If so, what is the best way to ensure the car will pass that test? Thanks. Steven
evap test if you open your tank to put a new pump.i hope you change your rubber gasket new and not use the old because that how they leak the max leak is .040...if you havent open it.you should be ok.oh yeah look for crack hoes..
Our cars have open evap systems. How are they checking for leaks? I'm assuming that the new tests are on OBD2 cars only.
Most OBDII incorporate a monitoring system of measuring evaporative emissions sysem leaks. The EVAP test is for 1995 and earlier. EVAP system is not open, it's closed. An inert gas pressurizes the tank (through a fuel cap adapter), the vapor line to the canister is plugged (with special pliers) or capped. Leak decay is measured between the capped vapor line and the tank.
I understand how an EVAP system works. I don't understand the point in testing a pre-OBD2 system for leaks. Our gas caps vent to atmosphere. Essentially all that's being tested is the tank, and the hose and line that goes to the purge solenoid. Seems pointless to me.
Our caps are only vented to atmosphere when a specific pressure is exceeded. Because OBDI is not tested by an EVAP monitor, California adds a test to measure leaks between the purge and tank. On the East coast CO is the main cause of non-attainment, but on the west coast, HC and NOx is the main cause of non-attainment. So a major source of HC can be attibuted to leaks occuring within the fuel system.
Reply That's correct most of the evap failures with the new test I see are incorrectly installed F/Pump sending unit seals. Also be sure the gas cap seal is good. If there is difficulty in finding a leak an authorized test & repair facility should have a device that enables them to fill the tank with smoke & get a visual indication of the leak source.
