EVAP failed emission test, california
Thread Starter
Intermediate
Joined: May 2008
Posts: 32
Likes: 0
From: Fair Oaks Ca
EVAP failed emission test, california
Failed the evap portion of the California smog test, 87 L98 with no mods.
check purge control valve and fuel tank relief valve.
I can blow the valves with or without vacuum applied.
The valves do hold vacuum.
Can't find any bad hoses.
Should I replace the valves?
If so where is a good part source?
Should I replace the canister?
Smog Test readings
15 mph, 1286 rpm, CO2 % 13.72, 02 % 2.03, HC ppm 36, CO % .05, NO 362
25 mph, 1286 rpm, CO2 % 13.39, O2 % 2.37, HC ppm 31, CO % .02, NO 298
check purge control valve and fuel tank relief valve.
I can blow the valves with or without vacuum applied.
The valves do hold vacuum.
Can't find any bad hoses.
Should I replace the valves?
If so where is a good part source?
Should I replace the canister?
Smog Test readings
15 mph, 1286 rpm, CO2 % 13.72, 02 % 2.03, HC ppm 36, CO % .05, NO 362
25 mph, 1286 rpm, CO2 % 13.39, O2 % 2.37, HC ppm 31, CO % .02, NO 298
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
The "charcoal" canister (evap) by the bumper has a filter inside of it. Try cleaning it out real good, double check your hoses, and take the car in when its running nice and hot.
You can find most of the valves and hoses at just about any local parts store (autozone) take your old ones with you cause there are many that look the same.
You can find most of the valves and hoses at just about any local parts store (autozone) take your old ones with you cause there are many that look the same.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You shouldn't be able to blow through the tank check valve (engine compartment, left frame rail) without vacuum on the output side. It's a check valve to hold fumes in the tank (when it isn't running) and that's what the pressure test is for. You passed everything else (and I presume no driveability issues), and if it was dumping fumes or raw gas into the intake (except when commanded) that can fatten up the mix to where it flunks the CO. As a side note, I continue to wonder how many tests/techs rupture the diagphram - they seem to pump quite a bit of pressure into the tank and when these valves fail you often end up with a canister full of gas. Seems you went in with a good running/clean Vette, so whatever happened may have been a recent occurrence.
Thread Starter
Intermediate
Joined: May 2008
Posts: 32
Likes: 0
From: Fair Oaks Ca
update on test performed
The tech said they clamp off the vapor line right before the check valve.
The tech clamp off the line in two places, the rubber line that goes in between the metal lines coming from the tank and leading to the check valve and the rubber hose in front of the check valve.
So I will have to take the car to someone that has a smoke machine to see where the leak is occurring.
I can only see a few paces the leak could occur as the majority of the vapor route is metal with a few short rubber hose sections.
Also the sending unit/fuel pump bolts are tight
I still need to replace that check valve.
The tech clamp off the line in two places, the rubber line that goes in between the metal lines coming from the tank and leading to the check valve and the rubber hose in front of the check valve.
So I will have to take the car to someone that has a smoke machine to see where the leak is occurring.
I can only see a few paces the leak could occur as the majority of the vapor route is metal with a few short rubber hose sections.
Also the sending unit/fuel pump bolts are tight
I still need to replace that check valve.
Last edited by tttjump; Apr 21, 2009 at 09:58 PM. Reason: add more information
Racer
Joined: Jun 2006
Posts: 361
Likes: 6
Same problem here and was also told by the tech it was the canister or check valve. Turned out to be a very small piece of hose that bridges two hard lines just in front of the drivers side rear tire. The rubber was deteriorated and was allowing the vapors to escape. I had to remove the tire to get to it and look real hard. Replaced tubing and passed.
Advanced
Joined: May 2003
Posts: 96
Likes: 0
From: Moreno Valley CA
Same problem
I have a stock 87 which failed the fuel evaporative test. What I found on mine was one of the hoses coming from the fuel tank to the charcoal filter had a hole in it.
I replaced all of the hoses with new. then one hose that had failed was located by the driver's side rear wheel in the bundle of tubing and wire harness for the anti-skid brage system. Once all of the hoses were replaced, I removed the hose to the charcoal canister and placed 15 inches of vacuum on it. The smog check people place 30 psig nitrogen gas in the system throught the fuel cap. If you can hold that amount of vacuum you should be able to pass the fuel evap test in the state of Calif.
I replaced all of the hoses with new. then one hose that had failed was located by the driver's side rear wheel in the bundle of tubing and wire harness for the anti-skid brage system. Once all of the hoses were replaced, I removed the hose to the charcoal canister and placed 15 inches of vacuum on it. The smog check people place 30 psig nitrogen gas in the system throught the fuel cap. If you can hold that amount of vacuum you should be able to pass the fuel evap test in the state of Calif.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
They may have clamped the lines (I didn't watch when they did mine last November), but did they release the pressure before they removed the clamps? I know when I removed my gas cap for a fillup after the test, I got a whoosh like it had never had before - made me wonder how much they juiced it.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Ok - my curiosity got the better of me so I went and looked at the BAR site. Somewhat confusing, but the FAQ's are here: http://www.bar.ca.gov/80_BARResource...s/LPFETFAQ.pdf
Seems they're suppose to crimp at the canister or as close to it as they can get and they even acknowledge that they might damage something! It would seem unusal to crimp at the Checkvalve or even before the canister because the law is to verify the integrity of the sealed system, but not the purge function (which it should only do when it's running). Oh well, hope you find an easy fix.
Seems they're suppose to crimp at the canister or as close to it as they can get and they even acknowledge that they might damage something! It would seem unusal to crimp at the Checkvalve or even before the canister because the law is to verify the integrity of the sealed system, but not the purge function (which it should only do when it's running). Oh well, hope you find an easy fix.
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Ca. ****'s
Same problem here and was also told by the tech it was the canister or check valve. Turned out to be a very small piece of hose that bridges two hard lines just in front of the drivers side rear tire. The rubber was deteriorated and was allowing the vapors to escape. I had to remove the tire to get to it and look real hard. Replaced tubing and passed.
The first one is next to the gas cap. Take boot off and look left.
Next one is by differental pumkin. Next one is the one mentioned here, in front of back tire. This is the most common one. Last one goes from by driver exhaust manifold wich goes to the canister.
2nd test will only be a partial if you passed everything else the first time.
Thread Starter
Intermediate
Joined: May 2008
Posts: 32
Likes: 0
From: Fair Oaks Ca
just found the small hose
I just found the small hose in front of the rear driver side tire. It is gummed up. The leak test is .46 and I need .40 to pass.
Going to change it out.
All together there are 5 hoses.
one from the sending unit to a tee fitting, tee fitting to steel line on top of gas tank, one hose next to pumpkin, one hose in front of rear driver side tire, one hose next to driver side front tire.
Two of the five where gummed up.
Wasn't there a recall on those hoses a while ago?
Going to change it out.
All together there are 5 hoses.
one from the sending unit to a tee fitting, tee fitting to steel line on top of gas tank, one hose next to pumpkin, one hose in front of rear driver side tire, one hose next to driver side front tire.
Two of the five where gummed up.
Wasn't there a recall on those hoses a while ago?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
"Wasn't there a recall on those hoses a while ago?"
I found these 2 Campaigns:
86-C-26 - Inoperative Pressure Control Valve - CA Emissions - '86 Models VIN'S G5101039 through G5907270 - replace valve
89C25 -'88 & '89 Models - deteriorated, cracked and/or leaking evaporative hoses - dealer to inspect and replace with new hoses and clamps. Another Bulletin is referenced here - #3D17 - I can't find what that one had to say or whether it applied to other Years, though it may have been applicable to other makes. I don't, for my '89, have any record of being notified of this Recall so I'm wondering if it too might have been for certain VINS only.
More might be available at www.nhtsa.gov or www.alldata.com might still show Recalls for free (Bulletins will cost you a subscription fee).
I found these 2 Campaigns:
86-C-26 - Inoperative Pressure Control Valve - CA Emissions - '86 Models VIN'S G5101039 through G5907270 - replace valve
89C25 -'88 & '89 Models - deteriorated, cracked and/or leaking evaporative hoses - dealer to inspect and replace with new hoses and clamps. Another Bulletin is referenced here - #3D17 - I can't find what that one had to say or whether it applied to other Years, though it may have been applicable to other makes. I don't, for my '89, have any record of being notified of this Recall so I'm wondering if it too might have been for certain VINS only.
More might be available at www.nhtsa.gov or www.alldata.com might still show Recalls for free (Bulletins will cost you a subscription fee).
Thread Starter
Intermediate
Joined: May 2008
Posts: 32
Likes: 0
From: Fair Oaks Ca
looks like problem is solved
Earlier I replaced the two hoses that had deteriorated, 5 hours later I remove he gas cap to see if any pressure had built up, upon loosening the gas cap I heard the pressure release from the tank.
Smog retest in the morning.
Smog retest in the morning.
Heel & Toe
Joined: Feb 2008
Posts: 21
Likes: 0
From: Buckeye Arizona
Hey guys I have the same problem going on with my Fuel Evap System...didnt pass emissions cause of it and I know I can do a better job of replacing the needed hoses if I can get pictures of where the hoses are located. If anyone can take the time to take pictures of the rubber lines and any of the lines/hoses I need to look at and replace please do so....you would be saving me and my C4... 
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
only things that you can fail the evap on is
leaking sending unit gasket
loose hose clamps
pin hole in the tank
pressure relief valve for the tank
purge line leaking
check all them rubber hoses back by the tank and those rubber hoses up by the drivers side fender.
leaking sending unit gasket
loose hose clamps
pin hole in the tank
pressure relief valve for the tank
purge line leaking
check all them rubber hoses back by the tank and those rubber hoses up by the drivers side fender.
Actually I just leeched off of someone else's thread since I didnt want to make another post...I live in Phoenix, AZ...yeah yeah same difference..
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA