BMW Fuel Tank Vent Valve - Genuine BMW 13901726705

Car: 95 BMW M3 - Production 4/94. OBD1. ----->Engine Code CEL 1263, only showed 2x even with bad purge valve. (New cel after this, with it still bad - 1221) Worked great once I understood how it worked - its not the way you would think. (Given its normally open, when most cars have it normally closed, go figure first gen Evap system on BMW OBD1). TESTING: NORMAL OPEN at under 1 psi (No POWER) light lip pressure will allow air to flow to Carb. TESTING: Powered CLOSED (MUST HAVE Full 12v to test) A 9v battery will not be enough, and it will fail the test!!!, USE CAR BATTERY with fuse in line. Normally OPEN without POWER to less then 1 psi. (light lip pressure) CHECK Valve always there - Air can only flow towards Carb. (At Least 15psi) TEST POWER APPLIED: It should Close when running(with power), at least 15psi - YOU can not blow this hard, if you can blow air through it, it failed. (this is where a 9v battery will also make it fail, you hear it work, but does not seal., must be 12v). Test blowing in both directs. Mainly towards Air Intake/Carb. It should be sealed in both directions when Powered. TEST, you can suck from the carb feed to test. But I would rather not take the chance something will be inhaled, so blow from the other side. ( I did suck test, but only using cheeks, not my lungs, and it worked as expected at under 1 psi, when not powered. And when powered, by cheeks could not do it, nor my lungs blowing - Thus sealed. May be better to use Garage Pressure Tank with regulator under 16psi, but lips proved old one bad, new one good. TEST CANISTER for air flow since your there. Air flow is restricted due to carbon media, but not so much it takes pressure to move air through it. 3 lines feed Canister. 1: Gas tank vent into canister, 2: Vent to Air from Canister bottom of car, 3: to Purge valve to suck the gas fumes to the engine and thus clean charcoal/carbon media. Good Luck: This was only part of my problem that came up tracking CEL 1263, that then spawned the famous 1221..... Still fighting 1221 currently (o2 sensor Rich/Lean condition). Given the purge valve was probably not enough to trigger o2 sensor depending on how long its been bad (orig 26 years old) - IT VERY WELL COULD, AND SHOULD. Its not only unmetered air, ITS AIR WITH GAS VAPORS - 10x MORE confusing for the DME to deal with than just air from 13mm air gap from the fuel line being unmetered. This should cause the o2 sensor to trip 1222 and/or 1221 cel. I seem to get one 1222 code preceding the 1221 codes after clearing codes and re-testing. Then all new test just show the 1221 code. PS: Sucking with lungs to test parts, you learn this lesson only once in your life (you hope)...... For me it was foam insulation - I will never forget...