When we think of
automotive emissions, we often think of the dirty stuff coming out of our
exhaust pipes. The internal combustion process creates noxious chemicals (like
CO2 and nitrogen oxides) that are released into the air as we drive. But
tailpipe emissions are controlled using a variety of systems like catalytic
converters and exhaust gas recirculation systems, and they're regulated by
state and federal legislation.
However, did you
know that there's another type of emission that comes from our cars? They're
called evaporative emissions. The gasoline in your fuel tank and in you fuel
lines slowly evaporates over time, releasing volatile organic compounds into
the air. The Environmental Protection Agency says there are enough of these
emissions to contribute to air pollution and pose a health risk to humans.
Because of their
harmful nature, the government also regulates these evaporative emissions in
new vehicles. This means that carmakers are required to install evaporative
emissions control systems onto every new car and truck they build. These
systems have been in place since the early 1970s. But as technology advances,
car companies find newer and more innovative ways to mitigate pollution. I’ll
tell you how evaporative emissions control systems work, and ways you can
prevent your vehicle's fuel from evaporating under certain conditions.
Controlling Emissions
The fuel we put
in our cars contains more than 150 chemicals, including benzene, toluene and
sometimes even lead. These ingredients can cause dizziness, breathing problems
and headaches when they're inhaled. Inhaling large amounts of gasoline fumes
can even cause death. On top of all that, evaporated gasoline is one of the
leading causes of smog and air pollution.
For these
reasons, carmakers are required to install systems on their vehicles that help
mitigate gasoline evaporations. Environmental regulation in the United States
began in earnest in the early 1970s, and as a result, cars have had evaporative
emission control (EVAP) systems ever since. These systems are designed to store
and dispose of fuel vapors before they can escape into the atmosphere.
A typical system
consists of a small canister full of charcoal, valves, hoses and vents in the
fuel lines and a sealed fuel tank cap. When fuel evaporates inside the gas
tank, the excess vapors are transferred to the charcoal canister. They're
stored there until they can safely be transferred back to the engine to be
burned with the normal air-fuel mixture.
When that's
ready to happen, a valve creates a vacuum that draws the vapors into the
engine. Fresh air is also drawn in through the vents and valves to mix with the
vapors for better combustion. These systems can be controlled mechanically, or
like on most on newer cars, through the engine's computer. The computer tells
the valves when to purge the canister of vapors. This typically happens when
the car is in motion, rather than at idle. As you may
expect, things can go wrong with the EVAP system, too. If the canister fails to
purge or does so under the wrong conditions, it can hamper the performance and
emissions of your vehicle.
Keeping Gas Evaporation Down
It's no secret
that gasoline is volatile. And it evaporates quickly, too. In fact, your car's
fuel can turn from a liquid into a gas at a very fast rate, especially when
it's hot outside. This is bad for the environment, with 20 percent of all
hydrocarbon emissions from cars coming from fuel evaporation. It's bad for your
wallet, too. Unless you're an executive at an oil company, you probably aren't
a fan of the way gas prices have been on a steady rise over the past few years.
It's bad enough that your car burns gasoline, why do you also have to lose more
to evaporation? The good news is
that there are things you can do to your gasoline to slow the process down from
evaporating. First and foremost, make sure your fuel cap is secured tightly. Fuel
can escape right out of your tank if it's not airtight. Whenever possible, park
in the shade during the summer months. Even though modern cars have advanced
EVAP systems to prevent too much evaporation from occurring, gas does still
evaporate from the tank, especially when the car is parked in the sun. This is
even worse when it's extremely hot outside. Parking in the shade helps keep the
entire vehicle cooler and reduces fuel evaporation.
Buy your gas in
the early morning or later at night. It's warmer in the afternoon and early
evening, which means evaporation is more prevalent. That's why you're sometimes
hit with that nasty gasoline smell at filling stations during the heat of the
day.
P0440 OBD-II Trouble Code
This indicates
that a part of the EVAP control system is no longer functioning correctly. The
EVAP system consists of many parts, including (but not limited to) the gas cap,
fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission
control system prevents the escape of fuel vapors from a vehicle's fuel system.
When the engine is running a purge control valve opens allowing intake vacuum
to siphon the fuel vapors into the engine. A code P0440 could mean one or more
of the following has happened: The gas cap is not installed or working properly
the purge solenoid has failed the canister is plugged and not working properly
Possible
Solutions with a P0440 OBD-II trouble code, diagnosis can be tricky at times.
Here are some things to try:
- Remove and reinstall the gas cap,
- Clear the code, and drive for a day and see if the codes come back.
- Inspect the EVAP system for cuts/holes in tubes/hoses Inspect for damaged or disconnected hoses around the Evap purge solenoid
- Check and/or replace the sensor
- Check and/or replace the purge valve Have a professional use a smoke machine to detect leaks
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