What Makes a Car Stall in Warm Weather?

by Edmund GaryUpdated July 17, 2023
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Nothing is more frustrating to a motorist when his or her vehicle stalls. The stalling may result from a fuel or a sensor related problem. The timing of a stall is never convenient, and can be dangerous. A vehicle can stall anywhere. Have the problem checked out after the first occurrence.

Hall Effect Sensor

The Hall Effect sensor can be the source of a stalling problem. This problem usually shows up on Chrysler model cars built before 1996. This sensor sends pulses to the logic module each time a shutter passes through the sensor, according to Allpar.com. The shutter represents the position of the ignition timing. If the computer does not receive any data from this sensor, it will assume that the engine is not running. The location of the Hall Effect sensor is located under the rotor in the distributor body. Distributors were eliminated in 1997 and newer cars.

Fuel Injectors

Fuel injectors use a cone shaped spray pattern to dispense the proper amount of fuel into the combustion chamber. Dirt, poor quality fuel and wear can cause the fuel injector to perform poorly or not at all. The spray pattern can be uneven. Instead of the smooth performance you expect from the engine, you get bucking or stalling. You may not be able to restart the engine after it stalls.

Fuel Filters

A clogged fuel filter can be a source of stalling. Fuel filters prevent dirt and moisture from entering the fuel injectors. Fuel filters should be replaced periodically, because their symptoms can mimic a faulty fuel pump. The symptoms are, rough idling, stalling and backfiring. The fuel filter is located near the fuel pump on fuel-injected cars. Locations of the fuel filter may vary in carbureted cars. They may be placed anywhere in the line between the fuel pump and the carburetor. Other locations can be directly on the carburetor.

Fuel Pump

A car needs 30 to 80 psi (pound per square inch) to start. Low fuel pressure can cause stalling, rough idling, misfire and hard starting. Fuel-injected engines are very sensitive to fuel pressure and fuel volume abnormalities, according to AA1 Car.com. Low fuel volume can cause the engine to start normally, but it will suffer from starvation while under a load caused by accelerating. This will cause the engine to lose power and stall. You can check the operation of the fuel pump when the ignition key is turned to the ON position. The fuel pump should buzz for one to two seconds.

Vapor Lock

The biggest warm-weather culprit for older cars is vapor lock. Vapor lock is caused by engine or exhaust heat vaporizing the fuel in the fuel lines or fuel pump, according to the "Reader's Digest Complete Care Care Manual". When the vapor reaches the diaphragm of the fuel pump, no fuel is fed to the engine until the fuel condenses again. Vapor lock is a symptom associated with carbureted cars which employed mechanical fuel pumps. These cars were primarily built before the mid-1980s.

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