1988 K1500 5.7L TBI - Emissions Debacle / FUEL TANK PRESSURE TEST / Evap canister?

[cragar62]

Hello all. I have TWICE experienced an emissions fail regarding the ARIZONA "Fuel Tank Pressure Test". Since I have confirmed through home testing that my fuel tank maintains pressure from the gas cap through all the lines up to the evap /charcoal canister, my question to anyone who may know is: "IS THE EVAP CANISTER DESIGNED TO HOLD TANK PRESSURE ?" "IS THERE A CHECK VALVE WITHIN THE CANISTER BODY @ THE VENT WHICH BLOCKS AIRFLOW?" I have attached an airflow line drawing and a photo of the evap canister in question to avoid any confusion as to what canister I'm referring to. Is the canister bad or are the folks at the emissions testing station wrongfully including the evap canister within the "fuel tank pressure" test? Any input will be greatly appreciated.

 

[pressureangle]

Hello all. I have TWICE experienced an emissions fail regarding the ARIZONA "Fuel Tank Pressure Test". Since I have confirmed through home testing that my fuel tank maintains pressure from the gas cap through all the lines up to the evap /charcoal canister, my question to anyone who may know is: "IS THE EVAP CANISTER DESIGNED TO HOLD TANK PRESSURE ?" "IS THERE A CHECK VALVE WITHIN THE CANISTER BODY @ THE VENT WHICH BLOCKS AIRFLOW?" I have attached an airflow line drawing and a photo of the evap canister in question to avoid any confusion as to what canister I'm referring to. Is the canister bad or are the folks at the emissions testing station wrongfully including the evap canister within the "fuel tank pressure" test? Any input will be greatly appreciated.

From
2018 Arizona Revised Statutes
Title 49 - The Environment
§ 49-542


H. Vehicles required to be inspected shall undergo a functional test of the gas cap to determine if the cap holds pressure within limits prescribed by the director, except for any vehicle that is subject to an evaporative system integrity test.

I could find zero reference to the actual testing methodology. I'd chase that down at my DMV to be sure they have it right; I once had to call the State Capitol DMV in Florida because some dummy thought a city bus park brake should hold at WOT. I did get an apology but it was a lot of aggro for every bus licence that went through that office before then.

 

[cragar62]

Aggravating is an Understatement. Been chasing my tail for a while now. Unsuccessful PHONE contact with anyone knowledgeable on the subject @ DMV or ADEQ or Emissions station itself (will not answer the phone). I'm going to have to go to the emissions station IN PERSON to determine just how they perform the "Tank Pressure Test" and determine whether or not they include the canister within the test parameters. If so (and I believe it is), It's a NO PASS scenario since from any info I've gathered, the EVAP Canister is not designed to hold pressure but is merely designed to sequester Evaporating Hydrocarbons within a charcoal medium to be purged into the throttle body upon engine startup. I wanted to be sure of this before I went down to the Emissions Station to give em' the what-for. Guess I'll continue my search for confirmation though I don't know of anymore stones I've left unturned.

 

[pressureangle]

If it was me, and I admit to zero knowledge of AZ policies, I'd challenge the testing center. Ask for the procedure, ask who trained them, and ask for the State complaint form we all know they have. Somebody will magically come up with some meaningful data.
AZ must have a Consumer Protection Department also, no? Every State I'm familiar with has a CPD for any licensed business.

 

[cragar62]

Just a little update, late as it is. My assumptions were correct regarding the emissions testing procedures as performed by the "Most High" Arizona Department of Environmental Quality on the EVAP system of my 88 K1500. Turns out that the emissions technicians ARE NOT PROPERLY TRAINED on earlier OBD1 vehicles and performed the EVAP test incorrectly (not once, but twice). After chasing a fart in the wind trying to replicate their findings, I ultimately came to the conclusion that they tested incorrectly and disputed their results. Long story short, I won, they lost. A "referee" retested my truck and passed it "with flying colors". So, to anyone from PHOENIX, ARIZONA....HEADS UP!! KEEP AN EYE ON THOSE "EXPERTS" and insist that they isolate the tank and evap line within the test parameters to the EXCLUSION of the EVAP canister. It will save you the grief that comes with the wasted time and $$. FYI

 

[PlayingWithTBI]

So, to anyone from PHOENIX, ARIZONA....HEADS UP!! KEEP AN EYE ON THOSE "EXPERTS" and insist that they isolate the tank and evap line within the test parameters to the EXCLUSION of the EVAP canister. It will save you the grief that comes with the wasted time and $$. FYI

I had the same fail on my 88 but, they did the test correctly. I had to do a smoke test to find a bad hose going to the Canister. Replaced it and passed no problem.

 

[GoToGuy]

In Calif the only vapor emissions are they test the cap for pressure control and vent. And tailpipe sniff the rest is visual on OBD 1. I don't know when the evap cannisters came into play for smog testing, but I have used the Snap On modis to cycle and test to ensure is working. On 2019 Mercedes.

 

[L31MaxExpress]

My 99 Tahoe had a canister vent solenoid from the factory while my 97 van did not. I added the vent valve to my 97 van along with the pressure sensor when I converted it to the 0411. I believe 98 is when the 1500s went to a sealed canister.

 

[someotherguy]

I had the same fail on my 88 but, they did the test correctly. I had to do a smoke test to find a bad hose going to the Canister. Replaced it and passed no problem.

That's wacky - so in AZ they're hooking up to your filler neck and pressurizing your fuel system through it to see if you have an evap leak? Here in TX when they were still testing OBD1 stuff (it's finally aged-out and exempt now), they'd just pull your gas cap and test it alone.

Richard

 

[PlayingWithTBI]

so in AZ they're hooking up to your filler neck and pressurizing your fuel system through it to see if you have an evap leak? Here in TX when they were still testing OBD1 stuff (it's finally aged-out and exempt now), they'd just pull your gas cap and test it alone.

yeah, we're California neighbors LOL. IIRC OBDI systems CAN get (depending on the inspector), visual inspections (including A.I.R. pump if OE supplied), gas cap vent, evap system, and rolling dyno sniffer. Their levels are lower than CA though. Mine used to pass with about 1/4 of their limits since it was originally a CA truck.