engine cranks but car won't start

Engine Cranks but Car Won’t Start – How to Troubleshoot

Got your coffee, got your breakfast, got everything you need for the day, and now it’s time to get going. You get in your car, you turn the key, it cranks but it won’t come to life. Looks like your engine cranks but the car won’t start. Not a great start to the morning, but these things happen sometimes. So what exactly is going on with your car? We’re here to help you diagnose what’s wrong with your car, as well as the repairs you might need to do and more.

Common Reasons Why Your Engine Cranks but Car Won’t Start

When your engine cranks but won’t start, that means the starter motor is working fine and the engine is “turning over“, but it won’t cough into life and run. Let’s make something clear first, the term “turn over” means that your engine cranks, but won’t turn on. A lot of people still often mistake the term “turn over” as the engine turning on and running, but mechanics define this term as the engine cranking.

Anyway, this is often an ignition issue, but there are other things that can cause this. If you try turning your key but your engine doesn’t even crank, then you might be looking at a starter motor issue. In which case, you can read more about it and how to diagnose it in our bad starter symptoms article. Here are several common reasons why your engine cranks but won’t start:

1. Your Car is Out of Gas

Yes, it can be as simple as this. When was the last time you filled up your car? Most people won’t forget to fill up their car with their gas as they have a fuel gauge telling them their fuel levels. However, your fuel gauge may display an incorrect reading, where the gauge is indicating the car still has fuel but has actually run out. For example, certain model years of the Nissan Rogue had this issue. It was quite a common problem from the car and many customers complained about it.

Unfortunately, most modern cars now have a fuel float mechanism that supports the sending unit. This prevents you from checking your fuel level with a dipstick. However, if you’re sure that you’ve filled up your car with gas recently and hasn’t run out, then something else is preventing your car from turning on.

In any case, if you believe that your fuel gauge is giving you incorrect readings or is behaving erratically, then you should check and fix it. You can diagnose it yourself or take it to your trusted mechanic.

2. Faulty Fuel Pump

A fuel pump, as the name suggests, is responsible for pumping fuel to your fuel injectors and then into your engine. The fuel pump can wear out over time, usually after about 200,000 miles for most cars. However, it can fail at 100,000 miles or even earlier if the car isn’t properly maintained.

If your fuel pump has gone bad, then it won’t be able to pump fuel properly. If your engine isn’t getting the fuel it needs, then it can’t start the ignition process which is what makes the engine run. We’ll talk more about the ignition process later on. If your car has done more than 200,000 miles or you haven’t checked your fuel system lately, then it’s possible you have a fuel pump issue.

3. Frozen or Bad Fuel Lines

Speaking of the fuel system, your fuel line may be the issue here. There may be a leak in the line that connects your fuel tank to your engine, this will prevent the fuel from getting into your engine. Which, similar to the fuel pump problem, will prevent the ignition process from starting thus making your car unable to turn on.

Depending on where you live, another issue you might face is frozen fuel lines. If you live somewhere that gets uncomfortably cold, then your fuel may freeze. As a result, it won’t be able to reach the engine. If this is the case, then you will need to thaw out the system first before your can start. To prevent this in the future, park your can indoors if possible so it won’t be exposed to the cold. If you have no choice but to park it outside, try not to leave it idle for too long and turn it on every once in a while to prevent the fuel lines from freezing.

4. Bad Ignition Coil or Spark Plugs

Unless you own a diesel car, your car has what is called an ignition system. The ignition system is needed to ignite the fuel and air mixture in your engine by using a spark. This will result in a controlled explosion inside your engine which powers the pistons and crankshaft, and this powers the car. If your ignition system fails, then the fuel and air mixture won’t combust and your car won’t turn on. A diesel engine doesn’t need this system as it relies on high compression to ignite the fuel and air mixture.

The ignition system comprises many components, but the two major ones are the ignition coil and spark plugs. The ignition coil is responsible for taking the low voltage power from your car’s battery, turn it into high-voltage electricity, and then feeds it to the spark plugs. Meanwhile, the spark plugs take that power from the ignition coil to create a spark at its tip. This will then ignite the fuel and air mixture, starting the combustion process and powering the engine. We found this great video from Donut Media you can watch if you want to learn more about ignition systems:

Ignition coils will typically last for 100,00 miles before it needs to be replaced. While spark plugs usually need to be changed every 20,000 to 30,000 miles or so. If you haven’t changed your spark plugs or ignition coils, you might be looking at this issue.

Engine Cranks but Car Won’t Start: Troubleshooting

Subaru Forester - Engine Cranks but Car Won't Start

So far we’ve established that there are four common reasons why your engine cranks but won’t start. Mostly to do with the ignition and fuel system. Of course, there are other possible causes such as incorrect ignition timing and compression loss. Now, we’ll guide you on how to troubleshoot an engine that cranks but won’t start.

Checking the Ignition Coil and Spark Plugs

To do this, you will need both an Ohm multimeter and a spark tester. We prefer to start by checking the spark plugs first, which means you will need to remove the spark plugs from the engine. Once removed, use the Ohm multimeter to test the resistance of the spark plugs. Here’s how to test a spark plug:

If the spark plugs are bad, then you will need to replace them. However, if they’re good, then it’s time to test the ignition coil.

There are several ways to test your car’s ignition coil, but our preferred way is to do a spark test. There are two ways to test an ignition coil depending on which type of coil your car has. If your car has a distributor-type coil, then it means the coil sits remotely from the engine and uses a distributor, which connects to the spark plugs by using a cable. You will need a spark tester to test this type of ignition coil.

Testing a Distributor-Type Coil

  1. Connect the “female” end to your spark plug and the other end into your spark plug wire/cable.
  2. Crank the engine.
  3. If the tester lights up, then that cable or coil still has enough spark.
  4. Repeat the process on the other cylinders.

Testing a Coil-on-Plug System

Meanwhile, the method to test a coil-on-plug system is slightly different. Most modern cars come with a coil-on-plug system or sometimes called the pencil plug. As the name suggests, these coils sit directly on top of the spark plugs and do not use a distributor. To check this type of coil, you will need a coil-on-plug spark tester. The steps are as follows:

  1. Remove the ignition coil you want to check and plug in the tester.
  2. Connect the ground wire to the engine.
  3. Start the engine and see if there’s a strong spark on the tester.
  4. Repeat the process on the other coils.

Here’s a video guide on how to check a coil-on-plug system:

We’ve written a comprehensive guide about ignition coil, from how they work, diagnosis, and replacement cost. You should read it if you’d like to learn more about ignition coils. However, if your coils are fine, then it’s time to continue our troubleshooting and check other components.

Checking the Fuel System

First, you’ll want to check the fuel pump (sender). Unfortunately, the fuel pump is located at the back of the car with the fuel tank. This means removing and inspecting it will require you to remove the fuel tank. What you can do instead is turn your key to the “ON” position, and listen for a hum. If you hear a hum coming from the back of the car, that’s your fuel pump working.

If you don’t hear the fuel pump working, then you should check the fuel pump fuse and voltage. This might be the reason why your fuel pump isn’t functioning. Next, you’d want to check the fuel pressure and you will need a fuel pressure gauge, which should cost you no more than $30. The steps to check your fuel pressure are as follows:

  1. Connect your fuel pressure gauge to the Schrader valve.
  2. Turn your key to the “ON” position, this will turn on the fuel pump.
  3. Your fuel pressure gauge should read 40 – 45psi. If it’s less than that, you will need to check the fuel pressure regulator and the fuel filter as well.

If the fuel pressure is fine, then the next thing you need to check is the fuel injectors. Ideally, you should use a mechanic’s stethoscope, but you can always use a screwdriver instead. To check the fuel injectors, locate the injectors, and then touch the screwdriver against the fuel injector. On the other end of the screwdriver, press your ear against it and have a friend crank the engine. If you hear a rhythmic clicking as the engine is cranking, then that means the fuel injectors are firing fine. Repeat this process on all of the fuel injectors to ensure that they’re all working.

Engine Cranks but Car Won’t Start: Checking Your Engine’s Compression

The next thing you want to check is your engine’s compression. You will need a compression tester to do this, which you can either buy or rent at an automotive parts store. Here’s how you do a compression test:

  1. Remove all of your ignition coils (or spark plug cable if you have a distributor-type coil) and all of your spark plugs.
  2. Insert the compression tester’s hose into the spark plug hole.
  3. Ask a friend to crank the car four times while completely flooring the accelerator pedal.
  4. Repeat steps 2 and 3 on each cylinder.

If the compression gauge/tester registers 90psi, then your cylinder has a healthy compression. If it’s below that, then there are a variety of issues that may cause this. Such as bad piston rings, a bad valve, or a crack on your engine. Identifying the exact cause can be tricky, so we recommend taking your car to your trusted mechanic for a diagnosis.

Engine Cranks but Car Won’t Start: Other Things to Check

There are several other things that you can check, such as your car’s air intake and ignition timing. These things can cause your car to be unable to turn on as well. We found a great guide on how to troubleshoot your car if the engine cranks but won’t start from ChrisFix, we truly recommend watching this video:

Engine Cranks but Car Won’t Start: Checking Your Car’s OBD

Okay, this is probably the simplest method and we should’ve begun with this. However, unless your check engine light was on in the first place, this method might not work in identifying why your engine cranks but won’t start. Anyway, the On-Board Diagnostics or OBD is a system in your car that reports if there is any problem with the car. When the OBD registers an error code, it will usually light up the check engine light. But even if your check engine light isn’t on, it doesn’t hurt to read the OBD and check for error codes.

To do this, you will need to use an OBD scanner. Be sure to check whether your car uses an OBD-1 or OBD-2 scanner. OBD scanners vary in prices, but a simple one for around $100 for personal use. Here’s how to use it:

  1. Locate your car’s OBD port, this is usually underneath the dashboard and you will need to remove a panel covering it. Keep in mind some cars have their OBD port in the engine bay.
  2. Plug your OBD scanner into the port and turn it on. You may need to enter some information such as make, model, and VIN. Afterward, scan for error codes.
  3. If you have a more complex scanner, then it may be able to display what the error codes mean. If not, then write down the codes (if any) and crosscheck them to find out what they mean.

Once identified, you can then proceed with the necessary repairs to fix your car. That being said, we’d like to remind you again that this method might not work unless there was a check engine light warning in the first place.

Engine Cranks but Car Won’t Start: Repair Cost Estimates

Since there are many possible reasons why your engine cranks but won’t start, the repair cost varies as well depending on what the exact problem is. They can range from $100 to even $2000. Here are some rough estimates and the cost you can expect to pay depending on the problem:

1. Ignition Coil and Spark Plug Replacement

These replacement jobs are among the cheapest on this list. Ignition coils usually cost around $300 to buy. While the labor cost is usually around $150, which brings your ignition coil replacement cost to about $450. Spark plugs are even cheaper, they’re usually no more than $50 for an entire set. While labor cost will vary between $40 – $100, which brings your total to around $150.

If you have the tools, we recommend doing these two replacement jobs yourself so you don’t have to pay for the labor cost. There are tons of tutorials online on how to replace different types of ignition coils. While a spark plug replacement job is fairly straightforward: remove old spark plugs, gap the new one according to the manufacturer’s specification, and insert the new spark plug.

2. Fuel Pump, Filter, and Injector Replacement

If you have an issue with the fuel pressure, chances are either the pump, the filter, or the injector is the culprit. A fuel pump is typically around $800 to replace including labor cost. While the fuel filter will normally set you back around $150 or so to replace. The fuel injector is the most expensive one here, as the cost can be as high as $1,200 depending on your car’s make and model. The labor is actually relatively cheap, at around $200 – $250, but the cost of the fuel injector itself usually already starts at $600.

3. Air Intake Issues

As the video from ChrisFix showed, your car may have issues with the air intake system that’s preventing the car from turning on. If the issue is just a dirty air filter, then replacing it should cost no more than $80 for most cars. However, if you have a faulty Mass Air Flow sensor (MAF), then you might be looking at a $400 bill, but this already includes labor. If the issue lies with your intake manifold, then replacing it will set you back between $400 – $600 including labor.

4. Compression Loss: Repair Cost Estimates

This is where it gets scary for your bank account. Compression loss is often caused by something not operating properly or damage to your engine’s internals. As mentioned, this includes bad piston rings, bad valves, blown head gasket, and several other possible reasons. The parts cost for most of these parts is not too expensive, but the labor cost is likely to be significantly higher than most other replacement jobs.

The reason is that these parts are the internals of your engine, and replacing them will require your mechanic to dismantle a significant portion of your engine. For example, to replace a blown head gasket, your mechanic will need to do the following:

  • Drain all oil and coolant from your engine.
  • Remove a significant portion of your engine, including the camshafts, cylinder heads, and the broken head gasket itself.
  • Clean the surface of the engine block and bolt holes.
  • Fit in the new head gaskets, the cylinder heads, and everything else that was taken apart before.
  • Set the camshafts and timing gears back to your car’s exact orientation, making sure it runs smoothly as it should.

As you can see, it’s a long and tedious process that can take a couple of days or more to finish. This is why a head gasket replacement job can be as high as $2,000. While a head gasket set is usually no more than $500, the labor cost can be as high as $1,500.

5. Ignition Timing Adjustment

Your car uses a timing belt to make sure the camshaft and the crankshaft are in sync. When they aren’t in sync, then the cylinders won’t fire correctly and your engine won’t run. Sometimes, the timing may be off simply because the timing belt was a bit loose, which causes the camshaft gear to skip teeth, throwing the timing off. If this is the case, you can watch the video from ChrisFix to diagnose and fix the issue. However, if you don’t feel like doing it yourself then a mechanic will usually charge you $70 to readjust the ignition timing.

Engine Cranks but Car Won’t Start: In Conclusion…

It’s never a pleasant experience when you get in your car all ready to go, only to find that it won’t start. Troubleshooting this problem may take some time as there is quite a lot of reasons why your car won’t start even when the engine cranks. If you don’t have the time to deal with this, then there’s nothing wrong with calling a mechanic and paying them to diagnose your car for you.

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