When your engine cranks, but fails to start, it could be, because of no spark.
No spark, is one of the most common reasons, why your engine will not start.
If your engine has no spark, you can crank the engine, as much as you want, but it will never start.
When taking on a no spark condition, one needs to be patient and have an open mind.
Becoming fixated on specific components, is a good way to not find the true problem. It’s far more likely that there is a problem with any of the following. Most often, a wire, connector, ground, or switch, than an actual ignition system component.
So, don’t focus on a single item, until testing indicates that item may be faulty. Knowing what to look for when troubleshooting ignition systems, can allow proper decisions to be made. First, we know your engine cranks but will not start.
Before doing any testing, always start with a fully charged battery.
First, Confirm Your Engine Has, No Spark:
- Disable the fuel system, by removing the fuel pump fuse or relay.
- Insert a spark plug tester, into the plug boot and ground it on a piece of metal on the engine.
- Finally, have someone crank the engine and watch for spark.
If the engine has a coil-on-plug ignition system with no plug wires:
- Remove one of the coils from the spark plug.
- Use an extra spark plug.
- A spark plug tester.
- Or even a screwdriver in the end of the coil.
- Ground it on a piece of metal on the engine.
- Finally, have someone crank the engine and watch for a spark.
- No spark indicates an ignition problem.
In extreme cases the (PCM) may have failed. In some cases, a (PCM) problem, will cause the vehicle, not to run at all. The (PCM’s) functions include; positioning the crankshaft and controlling the ignition spark and timing. If there are problems with how the (PCM) performs these functions, the vehicle may not run.
The Problem May Also Be Due To, Any Of The Following:
A Bad Crankshaft Position (CKP) Sensor
First of all, look for any broken, loose or corroded wires, from the sensor to the (PCM). The crankshaft position (CKP) sensor, monitors the position or rotational speed of the crankshaft. If the crankshaft position sensor has failed completely, it will not send a signal to the (ECU) at all. Then, the computer won’t send any fuel to the injectors. This will leave you unable to start the car.
A Bad Ignition Module
Ignition modules are solid state switching devices. And, they typically use a component, like a transistor, to switch the current flow on and off. In that way, an ignition module works a lot like mechanical points. However, ignition modules, are not able to do the job alone. An ignition module, requires some type of external input, in order to activate.
So, your vehicle may stall unexpectedly during operation and will not start again. Then, it is likely, because of loose or corroded electrical connections, in the ignition module. In this case, check the switch, clean oxidized terminals, and replace broken wires if necessary. Another problem is damage by overheating. If you cannot start the car, you need to test the ignition control module.
Other possiblitys are:
- A Bad Pickup Inside The Distributor.
- A Stripped Distributor Drive Gear.
- Broken, Loose Or Corroded Wires, From The Pickup, To The Ignition Module Or (PCM)
Electronic ignition pickups, are a component found on traditional electronic distributor ignition systems. They are located inside the distributor and function; as the trigger for the ignition system to produce spark. The pickup coil monitors the rotation of the distributor and triggers the ignition system. And, at the optimal moment to produce the best timed spark, for best engine performance.
As the ignition pickup essentially functions as, the activation switch for the entire ignition system. When, it fails, it can greatly affect the operation of the vehicle.
One of the first symptoms of a bad ignition pickup is, an engine that stalls and eventually will not restart.
Consequently, an old or failing ignition pickup; may cut out signal intermittently, which may cause the engine to stall. The engine may suddenly just shut off, almost as if the key had been turned off. Depending on the nature of the issue, sometimes the vehicle can be restarted and driven. Consequently, this problem will only get worse and completely fail.
A Bad Ignition Coil
The ignition coil is the unit that takes, your relatively weak battery power and turns it into a powerful spark. One of the most common symptoms of a faulty ignition coil. Consequently, is when the vehicle runs for a while and then the engine suddenly dies, for no apparent reason. As a result, this occurs after the ignition coil or module gets too hot. But, it could correct itself after the engine module cools. In some cases, a bad ignition coil, will result in the vehicle, not starting it all.
A Bad Rotor Or Distributor Cap (cracks or carbon tracks that are allowing the spark to short to ground).
Often the distributor cap is suspect. The internal and external surface of the cap should be clean. No erosion should be on the surface and the firing points, should be free of rust or corrosion. Also, confirm the rotor is in good working order. Consequently, it could short out the coil voltage and cause; a faulty connection inside the terminal of the distributor cap. The result is a misfire in the spark plugs. Look for any cracks or carbon trace in the cap.
A Bad ASD Relay
One of the most common symptoms of a bad ASD relay is, an engine that will start. But, stall out almost immediately, or at random times. So, the ASD relay supplies power to the vehicle’s ignition coils and fuel injectors. And, which are some of the most important components, of the entire engine management system.
So, if the ASD is having any problems that interfere with its ability to; supply power to the components. Then, those components may not function properly and problems may arise. A car with a failing or faulty ASD relay; may stall immediately after starting, or randomly while operating.
Faulty Ignition Switch
Normally, when you put the key in the ignition switch and turn it, you will have three positions:
- The first position, is the ‘off’ status.
- The second position, is the ‘on’ position, where the dashboard lights come on.
- The third position, is the ‘start’ mode, where you exert key pressure, to actually fire the engine up.
One major sign of a bad ignition switch is the instrument panel, not lighting up in position two.
NOTE: Suspect the (ECM) only as a last resort. So, if all other components are functioning properly, you may have a bad (ECM). At this point you should consider, taking your vehicle to a professional, to diagnose the problem.
Thank You !