How to Troubleshoot No Spark to the Engine

The starting process for a car consists of a series of closely timed events that begin in the ignition system. Once you insert your key into the ignition and give it a twist, three things happen: the starter motor comes on, the engine begins to turn, and the spark plugs begin to fire, or spark.

In order to generate the energy necessary for a vehicle to run on its own power, proper combustion must occur. So when you turn your car key in the ignition, the starter motor turns the crankshaft that moves the pistons in the cylinders. Once the engine cycle begins, it draws air and fuel into the cylinders. The air and fuel are then compressed, and combustion occurs when the spark plugs fire. This sequence is what creates the power to keep the vehicle running after the initial ignition.

Any delay or disruption of this process will prevent the engine from turning on. Timing is crucial for the sequence to create the desired result, and the spark plugs must fire at the correct moment of compression, or the engine will experience performance trouble, perhaps not even starting at all.

A car that won’t start can be a significant cause of worry for the owner. Engine repairs can be costly, and no car owner wants to have to think about replacing expensive car parts. There are several possible causes for starting failure, one of which is the lack of spark in the engine. If your car won’t start at all, this is a good beginning place for troubleshooting the problem. It is fairly simple to check whether or not your car has a spark, and you can run a few simple and inexpensive diagnostics to check this for yourself.

Remember that safety should be a primary concern when working on a vehicle. Always check the owner’s manual when troubleshooting any problems or working on vehicle maintenance. Make sure you have the proper tools for working on your vehicle along with access to a list of the correct replacement parts.

Check for a Spark in the Plugs

Since you will need to start your engine to check for a spark, make sure the fuel system is disabled; otherwise fuel will flood the cylinder without being ignited. You can do this by removing the fuel pump fuse or relay. Also check that your vehicle’s battery is in good condition and is able to provide power for ignition.

To begin troubleshooting for no spark to the engine of your vehicle, follow these steps:

1. 1.     Gather your tools. You will need an inline spark tester along with spark-plug pliers or other insulated-handle pliers. You’ll also find it helpful to have an assistant who can turn the vehicle on and off for you while you watch the engine for a spark. You may also want to wear heat-protectant gloves so you don’t accidentally burn yourself on hot engine parts.

1. 2.     Identify the location of the spark plugs. With the vehicle’s engine off, use the insulated pliers to remove a spark plug wire from the spark plug. Do not use your bare hands as you may receive a heavy electrical shock.

1. 3.     Insert the indicator end of the spark plug tester into the spark plug wire, and the other end to the spark plug. Have your assistant start the car while you observe the spark plug tester light. A constantly flashing light indicates the presence of a spark, while no light reveals that there is no spark.

Do not use a screwdriver for this test as it may increase your risk of electric shock and has the potential to damage expensive car parts, particularly on newer vehicles.

1. 4.     Repeat this process to check for a spark in each cylinder of your engine. If there is no spark in the plugs, the next step would be to check the coil. This is located in the engine’s rotor.

Check for a Spark in the Coil

To check the coil for a spark, you will need a digital multimeter.

1. 1.     Begin by removing the distributor cap and check for traces of oil. The presence of oil in the distributor cap can indicate a problem with the distributor itself. If it’s dry, then the distributor is operating correctly.
2. 2.     Remove the rotor, and locate the engine’s coil. Have your assistant crank the engine and observe to see if the distributer is turning. If it isn’t moving, then the timing chain or belt of your vehicle may be broken.
3. 3.     Using the multimeter, test both the positive and negative side terminals of the coil for resistance. Set the meter to 200 ohm, and connect the leads to the corresponding terminals–red for positive, black for negative. Check that the primary reading is in the correct range for your type of engine. You can find this information in your vehicle’s service manual.
4. 4.     Check the secondary coil’s resistance by setting the multimeter to 20K ohm and placing the black, negative lead in the center terminal of the coil. Again, check this reading to make sure it falls in the normal range for your engine type. This information should be included in your vehicle’s service manual. If the reading falls below the normal range, this suggests that the spark is weak or nonexistent. In this case, you will need to replace the coil with a new one. When you replace the coil, be sure to attach and tighten the leads correctly.
5. 5.     Clean up your work area and prepare to restart your engine. Replace any other parts you have removed in the process, such as the rotor and distributor cap. Wipe up any oil drips and remove tools from the engine area. Remember to enable the fuel system so your engine can run once started.
6. 6.     Now check to see if your vehicle’s engine will start successfully. Once you’ve completed these steps for diagnosing and repairing the cause of lack of spark in your engine, you should be able to start and drive your vehicle.

Troubleshooting for no spark in your engine is a simple and straightforward process that you can do yourself to save the expense and time of a trip to a mechanic. Follow the above steps and use safe practices, and you can quickly get to the bottom of the problem with your vehicle.