Skip the auto shop - Our mechanics make house calls

How to Fix a Car That Won’t Start

person looking underneath hood

Whether at home, work, school or out on a shopping trip, it's never a pleasant situation to sit down in your driver’s seat and find your vehicle won't start. It can feel like an overwhelming experience when you're not only trying to get the car started, but also trying to determine the cause.

Luckily, there are usually three common areas that can be investigated if you want to be proactive in discovering why your vehicle won’t start. The first area to be looked at involves testing the battery and the connections to the starter. The second is the fuel and fuel pump and the third, and usually the most common culprit, is issues with the spark to the engine.

Part 1 of 3: The battery and starter

Materials Needed

The most common reasons behind a car not starting usually reside with the vehicle's battery and/or its starter. Starting our investigation here will allow us to get to a solution more quickly on why the car is not starting.

To investigate a dead battery, we will want to start with the key turned to the “on” position. Go ahead and turn on the car’s headlights. Notice if they are strong and bright, if they are weak and dim, of if they are off completely. If they are dim or not illuminating, than the vehicle may have a dead battery. A dead battery can be jumped back to life with jumper cables and another car by following these steps.

Step 1: Park both vehicles close. Park the donor vehicle close to the vehicle with the dead battery. You will want both engine compartments to be near to each other so the that jumper cables can reach each battery end to end.

car jump starting another with jumper cables

Step 2: Safely attach the clamps to the terminals. With both vehicles off, open each hood and locate the battery for each car.

  • Have a friend hold one end of the jumper cables. Be sure that the two clamps do not touch each other.

  • Connect the red clamp to the positive battery terminal then the black clamp on the negative terminal.

Step 3: Now do the same for the donor vehicle. After the jumper cables are connected, start the donor vehicle and make sure all the accessories such as the heater/air conditioner, stereo, and various lights are all turned off.

  • These extras create a load on the charging system, often making it difficult to jumpstart a dead car.

Step 4: Allow the dead battery charge. Let the donor car continue to run for a few minutes. This is what allows the dead battery to charge.

  • After a few minutes, turn the key in the receiving car to the “on” position (do not start yet). Ensure that all of the accessories are turned off as well.

Step 5: Start the receiving vehicle. Finally, start the receiving vehicle and allow it to run. While it runs, have someone assist you in removing the jumper cables from each vehicle. Be sure to remove the negative clamp first, then the positive clamp.

Step 6: Drive the car for 15 minutes. Take the vehicle with the newly charged battery for a 15 minute drive. Doing this should allow the alternator to charge the battery fully.

Step 7: Have the battery tested. It’s a good idea to have your battery tested soon after this jump start to determine if it needs to be replaced.

  • Tip: A certified mechanic will be able to check out your battery if you do not have a battery tester. If the vehicle has a good battery but the engine does not turn over, the starter may be the culprit and will need to be replaced.

The starter can be tested with a digital multimeter placed on the signal wire between the starter and the battery. Have a friend turn the key and attempt to start the vehicle. While attempting to start, this wire should reveal the battery voltage it is receiving. If your power probe or multimeter is in fact displaying a battery voltage, you can rest assured that the wiring to the starter is good. If the starter is just clicking or not making any noise, then the starter is the culprit.

Part 2 of 3: Fuel and fuel pump

Step 1: Test the fuel in the vehicle. Turn the key to the “on” position and observe the gas gauge. In most cases, this will tell you how much fuel you have left in the tank.

  • Note: Sometimes the gas gauge can fail and and show that you have more gas then you really have. If you suspect low fuel is the issue, grab yourself a gas can and add a gallon of gas to the vehicle to see if it starts. If the vehicle does start, then you have discovered why the car is not starting: the gas gauge was inaccurate, it will need to be repaired.

person removing gas cap

Step 2: Test the fuel pump. Remove the gas cap and listen for the sound of the fuel pump turning on when you turn the key to the “on” position.

  • This step may require the help of a friend to turn the key while you listen.

Sometimes it can be hard to hear the fuel pump, so using a fuel pressure gauge can show if the fuel pump is working and also tell us if it is providing enough fuel to the engine. Most modern vehicles have an access port to plug the fuel pressure gauge into.

Observe the fuel pressure gauge while starting the vehicle. If there is zero pressure, the wiring for the fuel pump will need to be tested to make sure power is going to the fuel pump. If there is pressure, compare your readings to the manufacturer spec to see if it is in range.

Part 3 of 3: Spark

person pointing out spark plugs

Step 1: Check your spark plug. If you have adequate fuel then you need to next check for spark. Open the hood and locate the the spark plug wires.

  • Remove one spark plug wire and use a spark plug socket and ratchet to remove one spark plug. Inspect the spark plug for signs of failure.

  • If the white porcelain is cracked or if the spark plug gap is too large, then the spark plugs need to be replaced.

Step 2: Test with a new spark plug. To verify if the vehicle is receiving spark, take a brand new spark plug and insert it into the spark plug wire.

  • Touch the end of the spark plug to any bare metal surface to ground the spark plug. This will complete the circuit.

Step 3: Crank the engine. Have a friend crank the engine while you hold the spark plug to the ground connection.

  • Warning: Do not physically touch the spark plug with your hand or you can get shocked. Be sure to hold the rubber end of the spark plug wire to prevent getting shocked. If the vehicle has no spark, it is possible the ignition coil or distributor is the culprit and will need to be tested.

While the three most common areas have been provided, there really is quite a large number of reasons that could prevent a vehicle from starting. Further diagnostics would be required to determine which component is preventing the vehicle from starting and what repairs are necessary to get your vehicle back on the road.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Post a question and get free advice from our certified mechanics.

ASK A QUESTION

More related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
How Long Does a Vacuum Brake Booster Check Valve Last?
The braking system on your car requires a lot of pressure. The vacuum booster is one of the main sources of this pressure. This booster will take the pressure that...


Related questions

Q: Alt and Bat duplicate request

It is not normal for the battery and alternator to go bad in such a short time unless there is a problem in the wiring connections or harness connections. You will need to have the system checked to isolate the...

Q: Electronics don't work after jumpstart

Jumping a vehicle is a great way to receive instant power. On the other hand this can cause electrical issues if not done correctly. Multiple fuses can blow leaving you with a loss of power to many components in your...

Q: Does the OBD System Measure Gases in the Car's Exhaust?

The onboard diagnostic (OBD) system utilizes sensors mounted in the engine exhaust stream to measure the amount of oxygen that comes out of the engine after the combustion process. When an engine intakes a certain amount of air into the...