Don't overfill at the gas pumps

Q. If I keep filling even after the gas pump repeatedly clicks off, until the tank is completely filled, would this be harmful to my car?

A. At times, the gas pump auto-stop mechanism may trigger prematurely due to splashing or foaming from filling too fast. Pulling out the nozzle slightly, or filling slower, may help.

However, if the pump shuts off, then immediately shuts off when you try again, it’s likely full. Continuing beyond that isn’t advised since overfilling can flood the charcoal vapour canister (whose inlet is near the top of your gas tank fill pipe) with liquid gasoline, not to mention that fuel expands with temperature and might likewise flood the canister if a vehicle is overfilled then immediately parked.

If overfilling is taken to the extreme, fuel may even spray out onto the person operating the pump, or in the case of one recently destroyed million dollar luxury car, spilled fuel may hit a hot exhaust component and ignite.

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Eric Bristow of the Canadian Fuels Association adds:

Accidental spillage of gasoline from an overfill is both a waste of a valuable resource and, as it consequently evaporates, contributes to the formation of smog.

If you excessively top off your tank, beyond where the gas pump’s safety auto-stop kicks in, the extra gasoline may potentially foul the vehicle’s fuel vapour collection system, possibly resulting in your vehicle running with higher emissions.

Q. I’ve heard that ambulances and fire trucks must adhere to the posted speed limit when responding to emergency calls. Are police the only first responders exempted from speed limits?

A. In Ontario, under S. 128 (13) HTA, speed limit restrictions do not apply to:

• A fire department vehicle while proceeding to a fire or responding to, but not returning from, a fire alarm or other emergency call.


• A police department vehicle being used in the lawful performance of a police officer’s duties.


• An ambulance while responding to an emergency call or being used to transport a patient or injured person in an emergency situation.

Additionally, individual services may have internal policies regulating speed during emergency responses.

RELATED: Here's the proper way to react to a stopped emergency vehicle 

Q. Is it illegal to tailgate a responding fire truck to get through traffic?

A. Absolutely. Under S. 159(4) HTA, it’s an offence to follow within 150 metres of a fire truck with emergency lights and siren activated. For safety, please keep back of responding ambulances and police cars, too.



Freelance writer Eric Lai is a regular contributor to Toronto Star Wheels. Email your nonmechanical questions to him at wheels@thestar.ca . Due to the volume of mail, personal replies cannot be provided.