June 13th 2008
 

We're running into a lot of cars with "behavioural problems" these days.

Check engine lights coming on and giving a scan code related to the evaporative system. Usually this means that the gas cap
hasn't been tightened up properly. Hasn't been tightened "five clicks" as the vehicle instruction manual advises.

But the fuel supply system is more complicated than that.

Environmental regulations require that a system of solenoids direct any fumes generated by the gas tank back to a canister
containing activated carbon, instead of being vented to the atmosphere. These are known as carbon canisters.
The vapours are adsorbed within the canister, which feeds the resultant fluid into the inlet manifold of the engine.

With the price of gas being what it is and as the price fluctuates by as much as ten cents a litre day to day, so people are letting
their tanks run down to almost dry and then filling them as full as is humanly possible.

Which naturally entails force feeding.

This is the practice of pumping on the gas pump nozzle several times after the poor filling machine has indicated that your tank
is as full of gas as Al Gore is of bullshit.

This force filling saturates the carbon canister and causes it to malfunction.

If the fuel tank is rusty on the top, out of your sight, it can also force gas out of the top of the tank, to the exterior of the car.

If your tank is in good condition and all the solenoid valves are working properly, nevertheless, you can still flood your canister
which is under the hood near the air intake system.

Once the canister is flooded , it stops working and that crafty on board computer of yours knows this has happened.

On comes the dreaded check engine light and in a number of cases recently, the canister has been ruined, resulting in
a $400 (average) replacement cost.

So stop the force filling, when the nozzle shuts off, hang it up and be content that you got in at a good lower price,
at least this week.

Otherwise the extra $1 you "saved" can result in a repair job that can neutralize your gas savings by force filling for
another eight years - or so!