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Air Care News
January 2002

Fuel vapor leaks can cause HC failures with no OBDII codes
by Jerry Lyons

Over the past year and a half, several OBDII-equipped vehicles, mostly 1996 F-body GMs -- Camaros and Firebirds, have failed the I/M 240 emissions test for high hydrocarbons.

Now, we all know that OBDII should trigger error codes and illuminate the Malfunction Indicator Light (MIL) any time there's a problem, right? Well, in these cases there were no codes and no MILs. Just like two Bronco turnovers in the first quarter, these cars were shaping up to make for a long day.

Four of these vehicles were seen at the Aurora Emissions Technical Center. All had had their fuel pumps replaced. The vehicles were referred to the Technical Center because of HC failures in the 10 to 20 gram per mile category without an accompanying OBDII failure. The NOx was as low as it should be but the CO was also low, which is unusual when the HC is this high.

Investigation showed that each of these vehicles was in proper fuel control, and fuel trim was near or at center (zero percent fuel trim). However, each vehicle had a very strong smell of raw gasoline. When the fuel tank and evap systems were pressurized with nitrogen, none of the four vehicles’ systems would hold pressure as they should.

The gas caps were checked and were OK on three of the vehicles. A replacement for the one bad cap did not make that vehicle’s gas tank/evap system hold pressure any better. However, while the vehicles were on the lift, it was noted that the nitrogen could be heard hissing from a leak in the area above the fuel tank.

Remember that when running an I/M 240 test, the exhaust pickup cone is pulling in a large volume of air along with the exhaust. The exhaust pickup creates a flow of air that will register HC vapors from as far forward as the engine compartment area. We have seen leaky fuel pumps before, especially on older vehicles with mechanical pumps mounted on the engine, causing similar HC problems. With that in mind, it was determined that a major vapor leak near the gas tank was causing the failures in these vehicles.

Now, fixing these things can be messy. In order to get to the gas tank on these vehicles, the rear axle housing must first be removed.

The first two of these vehicles were repaired at the technical center because the hoses from the tank to the evap canister were disconnected in a fairly accessible spot near the canister, which is located in the left rear quarter panel behind the filler neck. The third vehicle was sent back to the shop that did the original fuel pump replacement because the hose had been left disconnected on the top of the tank. The final vehicle had a damaged filler neck hose. It seems that some technicians don’t completely remove the rear axle.

Apparently (kids, don’t try this at home), if the passenger side shock absorber and some other assorted hardware is removed, the axle can be dropped down far enough to snake the tank out, but only if the filler neck is bent down as it comes out. Of course the filler neck has to be bent back up as the tank is slid back in, with predictable stress on the weldments and filler hoses in the process. This repair tactic in this case strained the filler hose just enough to cause it to leak fuel vapor.

The OBDII system on 1996 GM F-bodies does not monitor the fuel evaporative system. We suspect that the repairing technicians "flat-rated" the repair, knowing that this model would not trigger evap codes, or perhaps the hoses are devilishly difficult to connect while raising the tank and they just forgot.

It is important to note that the problem of evap system leakage is not restricted to Camaro/Firebird vehicles, nor is it restricted to OBDII vehicles. The ‘gassy Camaro’ problem can be seen in other I/M 240 data – more than one hundred vehicles have failed for very high HC with low CO and NOx, and no MIL or error codes are registered.

The problem has shown up in other states with I/M 240 programs too. The important point is that any vehicle can experience evaporative system leakage from disconnected, cracked or broken hoses, leaky gas caps, canister breakout from over-full tanks, winter fuel in warm weather or any other thing that might allow gasoline vapors to escape from the vehicle. Any time one encounters a very high HC failure (10 grams or more), it would be smart to put the evap system through the possible diagnostic steps. Always verify fuel control first on any emissions diagnostic routine. On these cars, however, it was simply a matter of following the nose!

Jerry Lyons is an Air Environmental Systems technician with the Colorado Department of Public Health and Environment, at the Aurora Technical Center.

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Tow-away vehicle sales must meet emissions requirements
by Tom Myrsiades

In Colorado, a dealer may sell a vehicle as a "tow-away" due to safety concerns such as lights, wipers, windshields or tires, to name just a few. However, legal descriptions such as "tow-away," "inoperable" or "as is" may sometimes be confusing, as was the case with a consumer complaint recently reviewed by our office.

The complaint stated that a licensed Colorado dealer had sold a vehicle as a "tow-away." The vehicle was to be registered in the Denver metro area and would require a passing emissions certificate prior to registration.

When a vehicle is sold "as is" or as a "tow-away," an emissions certificate or voucher is required providing the vehicle is to be registered in an emissions area. Generally speaking, all used cars are sold "as is" unless a written warranty is provided. However the "as is" clause never relinquishes the emissions certificate requirement. Vehicles sold as "tow-away" fall under the safety requirements listed above and still require an emissions certification or a voucher when sold by a dealer.

The only exception is when the vehicle is actually inoperable due to a major component defect such as a blown engine or transmission. In that case, the seller must provide the buyer with a DR 2023 form – Notice of Emissions Non-Compliance. This document must describe, in detail, why the vehicle is inoperable and cannot be tested. Both the seller and the buyer must sign the form and each party retains a copy.

In the case of this complaint, the dealer sold the vehicle as "as is/inoperable" and gave the consumer a DR 2023 form. However, in the course of our investigation it was discovered that the vehicle ran and was driveable. The reason the vehicle had been sold as "as is/inoperable" was not because it was inoperable or untestable but because it would not pass emissions. This was clearly stated on the DR 2023 form the dealer had given the customer: "this vehicle will not pass an emissions inspection because it fails the CO portion of the test."

I love honesty, and realized that not all dealers fully understand the rules and laws concerning emissions test requirements. The dealer in this case was required to buy the vehicle back.

A good rule of thumb is that if a vehicle will start and drive, it probably will need a test or voucher. If a vehicle will not run, due to a blown engine or transmission, inoperable drive train or other major component, a DR 2023 form will be needed.

Used car sales may sometimes become difficult and challenging, but failing an emissions test is never an acceptable reason to sell a vehicle as "inoperable" or as a "tow-away."

Most cases are not generally this simple. Many scenarios exist and our staff is more than willing to answer questions. Please call us with your situation before it becomes a legal problem, 303-205-5603.

Tom Myrsiades is an Emissions Compliance Supervisor at the Colorado Department of Revenue.

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Emissions standards tightened for 2002; newer passenger vehicles affected
by Christopher Dann

It became a bit tougher for many newer vehicles registered in seven Denver metropolitan area counties to pass their biennial emissions tests this month.

Standards for hydrocarbon and nitrogen oxide emissions were tightened for 2002 as part of a planned change necessary to keep the Denver metro area in compliance with National Ambient Air Quality Standards.

Light-duty passenger vehicles are subject to the new, tighter standards. New vehicles manufactured within the last four model years remain exempt from the biennial emissions tests unless an ownership change occurs.

"This is an important step for air quality along the Front Range," said Jane E. Norton, executive director of the Colorado Department of Public Health and Environment (CDPHE). "These new tougher standards reflect changes in the makeup of the vehicle fleet that occur over time, and will help us to ensure that we continue to meet all the health-based air pollution standards now and into the future."

The changes mark the third time standards have been changed since the current emissions program was launched in 1995, replacing the older tailpipe-only testing program that had been in place since 1981. The legislation that created the current emissions program requires that standards be reviewed and changed periodically. The next round of changes is slated for 2004.

For example, beginning January 2, 2002, the hydrocarbon limit for 1996 and newer light-duty vehicles (passenger cars) is 1.2 grams per mile (gpm). Previously, the limit had been 2.0 gpm. For nitrogen oxides, the limit was changed from 4.0 gpm to 3.0 gpm. Carbon monoxide limits are scheduled to remain unchanged until 2006.

Norton noted that the changes reflect the passenger vehicles that currently make up the Denver metro area fleet. Every year, older vehicles are retired and taken off the road and newer, less polluting vehicles are introduced," Norton said. "Vehicles that were manufactured four years ago are now subject to testing for the first time. The tougher standards mirror the tougher standards that newer passenger vehicles are required to meet when they are manufactured. The fleet is getting cleaner, and our standards in Colorado need to ensure that these vehicles' emissions are within the guidelines they were manufactured to meet."

The standards change comes on the heels of major announcements by the State Department of Public Health and Environment during the summer and fall of 2001 that the Denver area has been designated by the U.S. Environmental Protection Agency as an "attainment area" for both carbon monoxide and ground-level ozone pollution.

That is, the area is now in full compliance with the federal standards for those two types of pollution. In order to achieve attainment status, Colorado had to submit documentation of current air pollution levels as well as long-term plans for how the area will continue to meet standards at least ten years into the future.

"The tighter emissions standards are part of both the carbon monoxide and ozone plans we submitted," said Doug Benevento, director of environmental programs for the CDPHE. "Periodic changes in the standards that vehicles must meet when they are tested are a key component of our overall strategy for keeping our air clean and healthy."

Seven Denver area counties are included in the enhanced emissions test program area. They are Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas and Jefferson. The enhanced program area utilizes a test known as the I/M 240, which is performed on a treadmill that simulates actual driving conditions.

Christopher Dann is the public information officer for the Air Pollution Control Division of the CDPHE.

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Gas cap replacement program wraps up

The end of September marked the end of the second successful "Put a Cap on Ozone" program. Evaporative gasoline emissions can account for up to 6 percent of volatile organic compound (VOC) emissions on any given day in the Denver metro area. This amounts to nearly three tons of air pollution per day. In the summertime, a faulty gas cap can allow one gallon of gas to evaporate every 15 days, and pollutants in evaporative emissions are a key ingredient in ground-level ozone formation.

To help curb these harmful emissions, from June 1 through September 15, 2001, the Regional Air Quality Council (RAQC), in conjunction with the Colorado Department of Public Health and Environment, Envirotest Systems Corp., independent emissions

Testing stations gave free gas caps or a $5 voucher good toward the purchase of a new cap to any motorist whose vehicle failed its emissions test due to a faulty or missing gas cap.

By the end of the 2001 program, approximately 12,000 gas caps had been replaced and over 2,000 vouchers for new caps had been given away with over 700 of those redeemed. It is estimated that due to these efforts, VOC emissions were reduced by 762 pounds per day.

In 2001 the program was expanded to test gas caps of employees at major employer sites. Nearly 500 gas caps were tested, with about 18 percent being replaced, at Roche Colorado, Hunter Douglas, Ball Corporation, CDPHE and at the Clean Cities/National Renewable Energy Laboratory.

The RAQC plans to continue the "Put a Cap on Ozone" program in 2002 with gas cap fairs at more employer sites next spring.

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