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Charcoal Canister

Old  March 14th, 2009, 8:01 AM
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Charcoal Canister

My 1995 Tahoe gave me a strong gas odor, and I found the top of the charcoal canister overflows with gas...this happen, mainly when I fill it up. Otherwise system is working ok, I do not find any cracked hose and the purge valve solenoid look to be working ok too. Any idea about what could be wrong? Thanks for help.

Old  March 17th, 2009, 3:04 PM
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For whatever reason, it's not being purged or someone is overfilling the tank.

Old  March 25th, 2009, 10:09 PM
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its a hard habit to break but when the pump first shuts off while filling , is when you should stop, don't go for that extra little bit to fill up the neck, or you can end up with just such an issue if that is the case...

Old  March 26th, 2009, 7:31 PM
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like in2pro said....when the pump stops, the tank is full...even if you can squeeze another $5 into it.
And you need a new charcoal canister now. They are ruined when they fiill with gas no matter what you try to do to save it

Old  March 28th, 2009, 4:37 PM
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Sorry to jump on this post luisvillar, but what is the harm in it being ruined? I understand it filters the gas going back to the tank or something like that, but how is it ruined if it fills up with gas? Is this the black canister next to the radiator on the drivers side? If so one of my hoses coming out of the top keeps popping off. Any ideas?


Old  March 28th, 2009, 6:21 PM
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Not sure of the location but it doesn't filter the gas. The filter does. What it does do is trap any gas vapors from the fuel system. Then when the engine is running, it burns those vapors. That's why you get a MIL when the gas cap is not tite. It's a closed system.

Old  March 28th, 2009, 9:29 PM
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Would this be the cause of misfire and running rough?

Old  March 29th, 2009, 10:41 AM
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probably not the mis-fire but could be a cause or running rough if a vacuum hose is loose.
A mis-fire is more likely a bad plug or wire, possibly a worn cap and rotor depending on the year model you have, guessing you have a pre-2000 as the canister was moved under the cab near the gas tank after 2000.

Old  March 29th, 2009, 12:22 PM
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I have to recognize I had the bad habit to fill it up to the neck, yesterday I filled up just to when pump shutted off first time and in my way back home I noticed the engine started to work as it was overflow with fuel and it quit working. The outside of the canister was complete cover with gasoline, I had a roll of absorbent paper which I used to wipe out the gas, then I disconnected the vacuum hose from the tbi and engine re-started again with no further trouble. When I got home a check the canister for more gas spilled over it but that was not to the case, it was dry. Approximately 20 minutes later I walked out of home and there was a strong gas odor, when I check the canister, again, there was a big spill of gas all over. I open the gas tank cap and it released a lot of pressure. I am afraid that even when I set another canister I only will be able to fill the tank to about 3/4 of it.
Thank you every one of you that have answered my request for help...

Old  March 29th, 2009, 2:30 PM
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Not entirely the same but very much related



What is ORVR?
Onboard Refueling Vapor Recovery(ORVR) is a vehicle emission control system that captures fuel
vapors from the vehicle gas tank during refueling.

How does ORVR work?
The gas tank and fill pipe are designed so that when refueling the vehicle, fuel vapors in the gas
tank travel to an activated carbon packed canister, which adsorbs the vapor. When the engine is
in operation, it draws the gasoline vapors into the engine intake manifold to be used as fuel.

How much will it cost?
EPA believes ORVR costs will be minimal. EPA estimates the additional cost (incorporated
into the purchase price of a new vehicle) to be between $6 and 8 per vehicle. This does not
include a projected annual fuel savings to the consumer of $2 to 4 per vehicle.

What are the benefits?
When fully phased in, ORVR controls will reduce volatile organic compounds (VOCs) and
toxics in the air by approximately 300,000 to 400,000 tons per year nationwide. VOCs are a
major cause of urban ozone, or smog. EPA also estimates an average of 78 million gallons of
gasoline per year will be saved between 1998 and 2020.

What if I have trouble refueling my car?
As the 1998 model year cars that have ORVR enter the marketplace, there is a slight possibility
that some car owners may experience difficulty refueling their vehicles. Some 1998 ORVR
vehicles (not all ORVR vehicles) may experience premature shut off problems at a very small
percentage of gas stations (1-2 percent of stations across the country). These nozzles at those
stations are being fixed or replaced by the nozzle manufacturers and service stations. New
vehicle owners who experience a problem should review and follow fueling instructions posted
near the dispenser. If the fueling problem continues, the customer should tell the service station
attendant about the problem. If the problem occurs at several stations (with different types of
nozzles), EPA recommends contacting your automobile service department.

Are they safe?
Yes. Automobile manufacturers have designed their ORVR vehicles to be safe. EPA and the
National Highway Traffic Safety Administration (NHTSA) review each vehicle manufacturer's
ORVR system design plans, prior to vehicle production, to assure compliance with Clean Air Act
requirements that vehicles do not "cause or contribute to an unreasonable risk to public health,
welfare or safety in its operation or function." NHTSA requires manufacturers to perform a
series of crash tests on all vehicles, including those equipped with ORVR systems, to
demonstrate crash worthiness safety. In addition, manufacturers indicate that they have
performed extensive testing on ORVR anti-pollution systems to assure that vehicles will be safe.

When is ORVR required on cars and trucks?
ORVR is required on 40% of 1998 model year cars, 80% of 1999 model year cars, and 100% of
2000 model year and later cars. Light-duty trucks have a six-year phase-in period, starting in
model year 2001.

Can I have it taken off?
No. Removal of emission controls would render that vehicle unable to meet EPA standards and
would be regarded as tampering, which is a federal, and, in many cases, a state offense.

Are any changes from my normal driving routine necessary?
ORVR systems are designed to be transparent to the customer and require no special refueling or
operating instructions. New vehicle owners should not notice any difference in the vehicle,
except that they won't breathe or smell harmful gasoline vapors during refueling.

Why do I need ORVR in my city or state if we already have Stage II vapor recovery
controls in place at the service stations?
ORVR is a nationwide program for capturing refueling emissions. ORVR systems on vehicles
are more cost-effective than converting all service stations, nationwide, to Stage II facilities.
Also, some small volume stations are not required to have Stage II vapor recovery units. After
ORVR vehicles are in widespread use (probably sometime after 2010) EPA intends to revise the
requirements so that Stage II vapor recovery controls would no longer be required at service
stations in most areas of the country, at a considerable cost savings to service station owners.

Where can I get more information?
EPA established a contact list. It is located at

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