What to do when your car refuses to start?


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This article will provide you with ways to properly diagnose your car if one day you find your vehicle refuses to start when you press the start button.

To fully understand possible problems in this situation, let me guide you through the process happening inside the electrical system of the car when you push the engine button.

First, the key will activate a circuit which transfers a small current to the neutral safety and the pedal switch, finishing by your pushing on the gas pedal to complete the circuit. The current then continues to go to the starter solenoid. From there, it signals the battery to transfer more energy to the engine and kickstart it. The car's motor would start to spin and the engine should crank at this point. If it doesn't, there's something wrong with the mentioned process.

1. The most common reasons

  • Malfunctioned car starter: You should direct a current to the starter to see if it spins, or get it fixed at an auto service. It may malfunction as a whole or just its teeth or other parts. In that case, try repairing the parts only.
  • Malfunctioned ignition switch: First, check if the electrical current get to the starter relay then look for the P/N switch and/or brake switch. You should try to crank up the engine by taking an electrical detour (by passing the switch) and direct the current straight to the engine to see if it would crank. Another way to test is sticking the voltmeter to the switch to detect the voltage. Also, check to see if the P/N switch, Brake and Clutch switch are closed.

ignition components inside car engine

These parts could be repaired partially, but they should be replaced completely if found dead

  • Inner engine damage or engine being hydro locked: In extreme cases, this is due to water getting inside your car. In other times, it's because the coolant finding its way to the engine from a faulty head gasket (the part used to prevent water from getting into the engine)

>>> See more: 5 things to do immediately after your car getting flooded

  • Bad wiring of the starter relay or the solenoid: You should tighten the wires and look for the sound when turning the key, if there aren't any sounds, ditch the relay and get a new one
  • Low battery energy: When you notice obvious signs of a dying battery, just recharge it or try to get some from other vehicles if possible.
  • Worn-out cables in the battery: You should tighten the cables and/or replace if it's too old

a mechanic checking car battery

Remember to check the battery wires and the battery itself, too 

>>> Also see: How to start the engine with a dead battery without using jumper cable

2. Problems with the fuel

Besides the above issues, there is a high chance that fuel condition causes your engine to break down. Below are common scenes in this situation:

Sometimes the anti-theft mechanism in your car could go off even though there's no outside threat to it. It will block the fuel stream from getting into the engine. Maybe there were some malfunctions in the electrical system or the circuit. 

  • Malfunctioned fuel pump and relay: If you don't hear any buzzing sound when igniting the car, it means that the fuel wasn't transferred to the engine.
  • Malfunctioned fuel injector: Sometimes everything is fine with the fuel tank, but the mean to deliver it is not. A damaged fuel injector might be caused by a failure in the injector relay or the fuse, and could prevent the current from getting to the injector and thus there's no fuel transfer to the combustion chamber
  • Lack of gas or contaminated gas: Sometimes the problem can be as simple as you forgetting to pump fuel into your car. And if it refuses to start even when you fill the tank fuel, your gas might be contaminated with foreign substances or water. 
  • Too weak or too strong vacuum pressure: This is due to a malfunctioned vacuum hose or valve that let in an unnecessary amount of air into the chamber, thus disrupting the air-fuel mixture. In this case, the engine can sometimes still start but it will crank very roughly. 
  • Malfunctioned fuel shut safety switch: Similar to the anti-theft mechanism, it could be activated when there's no real threat to it

Small Engine Repair: How to Check a Solenoid Fuel Shut Off Valve on a Kohler V-twin Engine

  • Open wires in the fuel circuit: It prevents the current from getting to the other side of the circuit. 
  • Plugged fuel line, filter and/or Pressure regulator leakage: Everything mentioned above is responsible for controlling and getting fuel pressure to a proper threshold so that the air-fuel mixture is properly mixed and burnt off completely. You should inspect and clean them periodically and ideally replace them altogether. 

A car fuel system

There are seemingly countless smaller parts in the fuel system, so be patient when examining them

3. Problem with the ignition process 

  • Failed crankshaft positioning sensor, ignition module or ignition coil: Failures in those components could disrupt the stream of voltage to it, thus preventing the spark plug to ignite and start the engine. On latest vehicles with an updated version of an ignition coil, luckily a bad coil only interfere with one or two cylinders so the car can still start.

4. Problem with the fuel-air compression force 

  • A failed cambelt, camshaft or malfunctioned catalytic converter will interfere with the valve opening timing, thus prevent the engine from running properly. In case the problem is with the converter, it could still start for several minutes, but can die off later. 

5. What to do when the engine cranks but refuses to start?

In this case, it might be the result of 3 following reasons: problems with the spark plug, with fuel compression and lack of fuel. First off, push the throttle open and then spray a special fluid that helps with the ignition process, and asks someone to start the car. If it runs for a few seconds then die off quickly, it's probably because of a lower level of fuel. If it doesn't start at all, the problem is in the spark plug. In that case, pull a wire off the spark off and place it close to a metal surface to help with its conductivity.

spark plug and ignition oil

You can do a quick test to check the health of the spark plug and the ignition coil

Warning: Get your hand off any part of the plug before starting the engine. When you've done all the things mentioned above and see a spark, the problem is the fuel or the compression force. If not, check the ignition circuit. 

Now bear with us as the process will involve checking back and forth the same components. Moving on to examining the fuel and compression force. You could know if the engine is getting fuel or not by hearing closely the sounds of pumped fuel inside and/or notice the burnt gas smell from the exhaust pipe. Also, lift the plastic cap that covers the fuel rail to check the pressure and also see if there's any gas in there. To be more specific, use the gauge to test the exact pressure force. If everything looks good, the problem is now back to the spark plug.

>>> Visit Car maintenance tips for more useful posts to take better care of your car!

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