Why is my car stalling?

We have all been there. It’s the end of a long day, your sitting in traffic, and then your engine begins to make a strange sound. Then, it’s dead.

Car engines stall and then quit because of a variety of issues involving air flow, fuel, and mechanics. When your engine stalls, it’s not only an uncomfortable event, but it can also cause unnecessary wear to your vehicle, and in some situations it can even be dangerous.

Diagnosing the cause of a stalling engine may seem complicated, but the truth is that all modern engines operate on the same basic principals. We highlighted some additional information below.

Diagnosing a Stalled Engine

Before attempting any diagnosis, review any recent work you’ve done or had done on the vehicle. This includes even something simple like changing your oil or other fluids. Evaluate the area in the engine compartment for any connectors or parts that you may have moved or displaced.

Some common reasons for motor vehicle stalls include:

  • An empty gas tank
  • A fuel mixture that isn’t rich enough (this is usually the cause of cold stalling and intermittent stalling)
  • A faulty fuel pump, alternator or EGR valve
  • A dead battery
  • A dirty air filter that’s preventing good airflow
  • Low fuel pressure (if your car only stalls on inclines this may be the case)
  • Problems with releasing the clutch (manual transmission vehicles only)
  • Coolant sensor reading hot
  • Ignition related problems such as loss of spark

Stalling while Driving

If the engine quits while you’re driving, the car will first lose power steering and then power brakes. Your first course of action should be to apply the foot brake and steer gradually over to the side of the road. Then, turn on your hazard lights and try to restart your car. If you can’t restart it, call an auto mechanic or friend with jumper cables for help. If the jumper cables don’t do the trick in rebooting your stalled engine, you may be looking at another problem that requires repair work.

If your engine stalls while your car is at an idle speed (idling means you’re sitting still), you might not be able to steer it to the side of the road. If this happens, turn on your hazard lights and call either the police or roadside assistance to help you safely get your car out of the road. Be sure not to get out of your car and try to push it while you’re in traffic. Your safety should be the number one concern!

Vacuum Leaks

Vacuum leaks are a common cause of engine stalling. To check for vacuum leaks, start with a visual inspection of the vacuum hoses and tubing. Professional technicians use expensive EVAP smoke machines to find vacuum leaks. These devices put smoke in the system which billows out at the location of the leak.

Engine Fuel

Check that the engine is getting fuel. An engine that is not getting enough fuel will stall out. This could be due to a failed fuel pump, clogged fuel filter, or simply not enough gas in the tank (don’t always trust your fuel gauge as it could be faulty).

To determine whether the issue is fuel related, begin by seeing if the vehicle will run on an alternate fuel source, such as brake cleaner. Spray the brake cleaner directly into the throttle body; if the vehicle runs the problem is fuel related.

Warning: Be careful when doing this! The engine can backfire causing injury. Engine damage can also occur if too much brake clean is sprayed in, resulting in hydrolock (when a liquid or solvent enters the engine, causing it to seize up) and a big repair bill.

If the problem is indeed fuel related, continue the diagnosis by checking fuel pressure. This is done by inserting a fuel pressure gauge into the pressure side of the fuel delivery system. On most gasoline port injected engines, fuel pressure should generally be between 40 and 50 PSI. It’s a good idea however, to consult the manufacturer’s repair information for the exact specification for your car.

Also, it’s important to note gasoline direct injected engines and diesel engines have much higher fuel pressures (thousands of PSI). These systems require dedicated gauges for testing as well as extensive safety precautions. In other words; testing these systems is best left to a professional.

Orange County Automotive Services

At Saddleback Automotive Service Center, we strive to provide you with an alternative to dealerships by providing the vehicles, and you, with excellent service and the best possible repairs.

We are continually updating and upgrading all of our diagnostic equipment in order to serve our clients confidently, knowing that despite all the changes in technology, we are prepared for any automotive challenges that come our way. Contact us below for additional information and to schedule a vehicle check-up!





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