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How to handle your vehicle when it stalls in traffic

Published:Sunday | August 18, 2019 | 12:11 AMPaul Glenroy Messam - Automotives Writer

As a driver, you are ready to roll. You turn the ignition. The engine starts but fails to keep running. This problem is related to the concept of stalling. Stalling occurs when an engine starts but fails to keep running.

“The condition is often referred to erroneously as hard starting if the engine stalls immediately after it starts,” says Delroy Campbell, auto mechanic. “In fact, an engine that stalls may become an engine that is hard to start if the condition is allowed to continue.”

The fact is, thermostatically controlled air cleaners have been installed since the early 1970s to reduce the amount of carbon monoxide generated by cold engines. A thermostat air cleaner does this by regulating the temperature of the air entering the carburetor. A damper door in the air cleaner inlet (snorkel) closes when the engine is cold. Therefore, no cold air can enter. Instead, warm air from the exhaust manifold is diverted through a tube to the carburetor.

This cuts down on carbon monoxide since less of the gas is produced when gasolene is mixed with air.

According to Campbell, if the damper door in the snorkel fails to close when a cold engine is started, stalling occurs because the engine is not calibrated to accept cold air. He recommends that in order to determine if the thermostat air cleaner is causing the stalling condition as a cold engine is being started, one should check the air cleaner by observing the damper door. Experts suggest that if one cannot see the damper door by looking into the nose of the snorkel, they should remove the air cleaner cover and filter element and check the damper door operation from the back side. This is the opportunity to also examine the filter element, which has to be clean and unclogged to prevent a stalling problem.

Let us examine briefly some other causes of stalling:

1. A split or loose hot-air tube from the manifold to the air cleaner. This will require replacing or reconnecting a defective vacuum motor.

2. A defective sensor. If applying vacuum and the vacuum motor closes, the damper door sensor is bad. Replacing the part is recommended.

3. A thermostat air cleaner malfunction causes both warm and cold engines to stall. So if the engine starts and warms up, the damper door should open. If it stays closed, the engine will stall. A defective sensor is usually to blame for the damper door staying closed when it should be open.

4. Carburetor idle speeds. The correct or slow and fast idle-speed adjustments are basic to a properly running engine. Idle speed should be adjusted to the specifications of the car manufacturer.

5. Contaminated fuel: Contaminated fuel refers to gasolene that contains water, dirt, or other foreign matter. The smart thing to do is disconnect the fuel line to the carburetor and allow some gas to drip into the palm of one’s hand. If the gas contains water, drops will remain after the gas evaporates. Usually, dirt or other foreign matter makes the fuel feel gritty as you rub it with your fingers.

6. A clogged PCV valve. This upsets the air-to-gas ratio, which results in stalling.

7. Vacuum loss. The engine must maintain vacuum to keep it from stalling and or idling rough.

8. An inoperative valve can also cause the engine to stall.