Engine not running or cranking over can be an easy fix
Is your engine not starting or cranking over? You have come to the right
place. We are a team of ASE certified mechanics who have created these
instructions which will help check the easy things first and then progress onto
the more difficult problems. We have included the two different problem
scenarios; the engine is not running and the engine is not cranking over. The
first section is for an engine that won't run. The second section is for an
engine not turning over.
What Goes Wrong?
An engine needs three things to run; Compression, fuel and spark. Because the
engine depends on supporting systems to make these things happen such as the
fuel and ignition systems a simple item such as a fuel pump relay will make the
engine not run. When the engine is not cranking over a simple item such as a low battery can fix the problem.
How much does it cost?
Troubleshooting an engine that does not run and does not crank over will be
different. If the engine is not cranking over and you have towed it to a repair
shop to troubleshoot the problem it should cost between $30.00 if it's an easy and $140.00 if
it a more complicated electrical issue. If the engine is not
starting then more diagnostic time maybe needed. Again, there are simple
and complicated problems for both of these scenarios.
Let's Get Started
This section is for an engine that cranks over but will not fire up.1. Check the Security System
A security system is built into most vehicles which disable the ignition or
fuel system when activated. Occasionally the system will simply become confused
due to a glitch or a procedural error. If the security light is flashing when
trying to start the car the system has been activated. Exit the vehicle and lock
all of the doors with the windows up and then wait 20
minutes. Then unlock the vehicle by the driver's door lock or remote this should
alarm system and then try to start the engine. If the light is still
flashing try the spare key. If the light then goes out it is because the
frequency chip located inside the first key has gone bad. This could be due to
age in which case you will need a new key from the dealership. If the light is
not flashing continue with our guide.
2. Test Fuses
Fuses are used to protect various electrical circuits while supplying power
to components such as the fuel pump, fuel injection and computer systems from suffering a short
circuit and possibly causing an electrical fire. When these fuses blow the system they
support stops working and the engine stops running. There are two methods of
checking electrical fuses that protect various
components. You can either pull each fuse out and inspect it by hand or
test light to check its continuity. If a blown fuse is found check the system it belongs to by
using the vehicles owner's manual or the identification chart on the fuse panel
cover. Once the system is identified remove and inspect or replace the failed
part and retry the engine. If the fuse still blows you will need to
wiring harness for damage or a broken wire and repair it. If all fuses are
good continue with our guide.
Fuse Test Video3. Check for Spark
The ignition system is designed to ignite the fuel air mixture inside
the combustion chamber via the spark plugs. This is done by using an ignition coil,
camshaft angle sensor along with the
car's computer or PCM
(Power Control Module). This system can stop working due to a failed ignition module or crankshaft angle sensor, or
worn spark plugs which is very common.
Testing the ignition system is an easy job that takes about five minutes and can be
done using a test light or an extra spark plug. Connect a test light to ground
and with one of the spark plug wires or coils disconnected. Crank the engine
over while holding the tip of the test light about 1/4 inch (7mm) from the wire
or coil terminal. Keep your hands clear of the test area to avoid
accidental shock (non lethal). You can also insert a spark plug into the coil or wire and
hold it against a metal ground. You should see a light blue spark in the
gap this is telling you the system is working. If no spark is present suspect
crankshaft sensor will need replacing which is the most common problem.
Test Ignition System Video4. Check for Fuel
The fuel system is used to deliver the proper amount
of fuel at the correct time of the cylinder's compression cycle. This is performed by the
injection system which consists of a fuel injector for each cylinder. A fuel
pump is located in the fuel tank with fuel lines that travel from the tank and up to
the engine and into the fuel rail where the
fuel injectors reside.
Common fuel system problems are due to a
fuel pump that
has failed and is not supplying fuel pressure. Or the
injectors are not operating
correctly allowing the proper amount of fuel to be distributed into each
cylinder for the piston to ignite. The easiest way to check if the fuel pump is turning on is to
be very quiet and switch the ignition key to the on position without
cranking the starter. You should be able to hear the pump running in the
rear of the car. If you are unsure of its operation then you will
test the fuel pressure. If no pressure is present then confirm the
being bad and needing replacement by using a wring diagram for your vehicle and probing the pump
power wire using a test light.
Fuel Pressure Test VideoFuel Pump Replacement Video5. Check Engine Trouble Codes
When a sensor or a controller fails in the engine computer system such as
a crankshaft angle sensor, ignition amplifier or fuel pump controller it will
stop the engine from starting. A check engine, service engine soon or MIL
is telling you there is a
diagnostic trouble code stored in the car's computer.
are designed to give you an idea of the system or sensor that is causing the
problem. When these codes are present it means the computer has
detected a failure which when corrected can fix the trouble. Today's cars are
easier than ever to read the codes and it does not cost much for a code reader. If
you do not have a code reader you can easily purchase one online from places like Amazon
for about $40.00 (US). Plug the code reader tool or scanner
into the ALDL port which is located on the driver's side near the bottom of the
dash in most cases and gather any codes that are present. The video below shows
a Honda Civic being done but it is the same for most cars.
Check Engine Codes6. Crankshaft Angle Sensor
A bad crankshaft angle sensor may not show up on a code scan as being faulty.
When this sensor fails the computer see's the engine as not turning which may
not be the fault of the sensor as far as the computer is concerned such as a bad
starter. These sensors are located either at the front, middle or rear
of the engine near the bottom of the block where the crankshaft resides.
of the crank sensor takes
about fortyfive minutes give or take depending on location and the accessories
that maybe needed to be removed to perform the repair.
Crankshaft Angle Sensor Replacement Video7. Check for Injector Pulse
Injector pulse is needed for the fuel to enter the engine through the
injectors. This test will let you know if the computer is working by
triggering the injectors for the engine to run. If there is no trigger then the
computer is not powered up from the ECM relay or some other electrical issue is involved.
Checking injector pulse can be done by using a test light while the
engine is cranking. This will
test if the injectors are getting a trigger signal from the computer.
8. Check Cylinder Compression
The engine requires compression to ignite the fuel to make the engine run. Cylinder compression is the result of
the proper correlation of the crankshaft and camshaft while the
pistons travel upward in the cylinder bore. When the volume of compression drops
below about 85 PSI combustion is not possible. Cylinder pressure can be affected by a misalignment
of the crankshaft and camshaft that can put the valve timing out of sync with
the pistons. The most common cause for this is a jumped timing belt or timing
chain. Checking engine compression is not too difficult and can be done with
a spark plug socket and a compression gauge which you can rent for free from
your local parts store. If compression readings are between 125 and 170 psi
the compression is normal. Most of the time if one cylinder has the correct compression
the engine will start and run. If one or more cylinders have low compression the
and have a rough
idle but still run. When the compression is low or non-existent the engine will crank over
freely with little resistance to the starter a sure sign the chain or belt is
Engine Compression Test Video9. Plugged Exhaust System
Engine exhaust must be able to be relieved from the engine to allow it to
run. If there is an obstruction such as a catalytic converter that has broken
and plugged the exhaust system no exhaust gasses will be able to exit the
engine. In this case
remove the exhaust head pipe to allow make sure the exhaust system is not a
What Makes An Engine Run?
For an engine to run it must have compression, the proper amount of fuel with
a spark at the plug at the correct time. Check out the video below to get an
idea on what needs to happen inside in each of the cylinders for the engine to
Watch the Video!
What to look for when the engine will not run. This video shows how a mechanic would tackle this problem.
Obscure Starting Issues
There a few subsequent conditions which are more difficult to detect which will cause your engine not the start and run such as:
Water in the fuel tank
Electrical system wiring harness failure
Car was driven through a deep water puddle causing electrical components to get wet.
Before your car would not start did you notice anything out of the ordinary
such as low power or a check engine light? This could aid in the troubleshooting and diagnosis
process. If you are taking your car in for repairs mention anything you noticed before the trouble began to your mechanic.
If the car stalls while driving and then starts back up immediately that is a
slightly different issue that will be able to fixed by visiting: Engine
stalls while driving
If the engine is hard starting while taking an abnormal amount of time to catch and run
then you need to follow this guide:
Hard starting engine.
Section 2: Starter is not working
You go out to your car you turn the key and the engine is not cranking over.
This is when you can lift the hood and do some checking to see if it is
something simple or a little more difficult. When the engine is not turning over
it can be mainly due to three separate areas of the car. First the area could be
the battery, next is the starter or its trigger circuit and finally a problem
with the engine or one of its accessories. Some of these things are easy to fix
while others can be a little tougher which we will describe in the following repair guide. We will go over each one of these issues
in order of popularity to show you the first things to check so we can get you back on the road.
1. Test the Battery
is a chemical based voltage storage unit that loses its ability to hold a charge
and delivery the amperage needed to operate the electrical system and more
importantly the starter motor. Between three and four years the chemical reaction
inside the battery will begin to break down and weaken it. One thing you need to know is the starter pulls a high amount of
electrical amperage from the battery to operate. When turning the ignition key to the crank position you may notice a few different scenarios which can mean the same problem:
You turn the key to the on position and the dash lights go out or are dim
You turn the key to crank the starter and it goes for a brief time but then it stops and you hear a loud clicking noise
The engine turns over slowly and then stops.
These are all signs the battery is down on charge.
Load test the battery to confirm its condition which can be done
using and observing the headlights of the car and by watching the video below.
If the battery warning light is not on while driving this means the battery is
probably being charged properly and it has lost its ability to hold a proper
charge. Avoid trying to crank the engine over when anyone is near the battery. A
battery is sometimes filled with explosive gasses that can ignite when extreme
heat or a spark is present.
Battery Test Video
If the battery tests bad and the battery light has not been on then the
battery needs to be replaced. Residual battery acid around the
top of the battery can be present so wear gloves and avoid touching your clothes
or skin when working on or near the battery. If needed use baking soda and a
garden hose to neutralize any acid residue before you begin replacement. If the battery fails its load test it will need to be replaced with a new or
good used battery of comparable size and cranking amps. You can get an Optima or AC Delco
replacement battery which last longer but cost a little more online from sites like Amazon which you
can get through prime in one day or just head on down to your local parts store for a replacement. Record radio preset stations for
re-entry before removing the battery. Here is a video on how to replace your battery.
Battery Replacement Video
If in the dash the battery warning light has been on prior to this repair and the battery is fairly new then the
battery will need to be
jumped to get the engine running so the alternator can be checked. Jump the battery
using jumper cables which you can purchase online from sites like Amazon. Be
careful not to connect the jumper cables backwards by connecting the negative to
the positive battery terminal or you can cause electrical system damage. This step is
necessary to test the alternator which will be in the next video.
Battery Jump VideoTest the
alternator voltage output once the engine is running. If the
alternator fails this test then it will need to be replaced.
Alternator Test Video2. Check Battery Cable Connection
The battery supplies voltage to the starter through positive and negative
battery cables which need to be clean, tight and free from corrosion. If you
know the battery is good because it is fairly new or you have tested it has
passed there could be a battery connection problem at the terminals or starter
motor itself. Here are the symptoms of a bad connection.
While the dash lights are bright you turn the key to engage the starter and the dash lights go out and nothing happens
The starter begins to work but then it suddenly stops and the dash lights go out and nothing happens.
The battery cables are used to transfer the battery voltage to the engine
starter and to the electrical system. These cables are subject to battery acid
which can produce an internal cable failure. Corrosion and loose connections
stop electrical current flow. When this condition occurs the car
will act much like a low battery by not allowing the voltage to continue to the
starter motor. Check both the negative and positive battery cables for abnormal
bulging, weakness or corrosion. This problem can be sometimes overlooked by most
mechanics and can be intermitted. These conditions cause heat which will produce the power disconnect. When the connection cools it can start
working again. Inspect the
battery cable ends for corrosion which means they
need to be cleaned. While wearing rubber or vinyl disposable gloves grasp
both negative and positive battery cable ends and try to wiggle them to check for tightness.
Then use a wrench or socket to loosen and remove the cable end. Be careful not
to touch the wrench or ratchet to any metal parts or the opposing terminal to
avoid a short circuit. If the end is badly eaten away by acid you may need to
use a pair of channel locks to work the cable end loose. Then replace the
battery cable end which you can get from Amazon or the local parts store.
3. Check Starter Fuse and Relay
Like most heavy electrical load components such as starter there is a fuse and
relay to protect the circuit. These components are usually located in the fuse panel or power distribution center
under the hood. If the fuse fails it will cause the starter to not operate. Likewise if the starter relay that follows
the fuse stops functioning because of an internal short circuit or the contacts
fail due to usage there will be no trigger voltage supplied to the starter solenoid.
Use a grounded test light
and locate the fuse panel to
test the fuse.
Replace any that have failed and recheck the starter operation. If the fuse
tests okay continue down the guide.
The starter relay is next in the circuit to supply power to the starter solenoid
which engages the starter motor operation. Some older vehicles are not designed with
this relay in which case you can skip this step. To be sure if your car is
equipped with one of these relays check your owner's manual or the fuse panel
identification information located on the lid of the panel. When this relay fails it can do so in two different ways.
First the relay may make a ticking noise like it is working but the contacts inside the relay are
burnt not allowing the power feed of the relay to be transferred through to the
starter solenoid. Next, the electric coil winding will fail causing an open
circuit not allowing the relay to work (no ticking noise). In either case the
relay must be tested and then replaced if found to be bad.
4. Test the Starter Solenoid Trigger Wire
Before the starter motor can work the solenoid that is responsible for its
operation must receive a voltage signal. This signal is the final destination
for the voltage which originates from the operation of the ignition switch by
the driver. If everything before this point tests or looks okay you will need to
test the starter motor trigger wire for power while the key is in the crank
position to determine the condition of the starter. In most cases it will require you to get under the car and located the starter motor which
is usually on the right or left side near the rear of the engine block and
sometimes under the intake manifold like on Nissan and Infiniti V8 engines.
Lift your car safely using a hydraulic floor jack and secure the vehicle
with jack stands to access the wire for testing. Once the vehicle is lifted locate the starter solenoid trigger wire which is the
smaller of the two electrical connections.
Connect a test light to ground and have a helper hold the key to the crank
position. Hold the point of the test light on the terminal of the trigger wire
on the solenoid the test light should light up. Then test the large power
terminal which is connected to the positive side of the battery it to should
also have power. Do not connect the test light probe to ground while checking
for power to avoid a short circuit. If both terminals have power the starter has
failed and replacement is required. Sometimes you will hear the starter click but not
activate. This is telling you the solenoid is working but the motor part is bad
in either case the
starter motor has failed and needs replacement.
If the starter is getting power and still not working you can try using a hammer while
the ignition key is held in the crank position and bang on the starter. This
will get the starter to sometimes work one more time.
Starter Replacement Video5. Starter Makes Noise But Still Not Cranking
Many abnormal noises can occur while the engine is not cranking over. These
noises include grinding, whirring or a loud clunk
indicate and mechanical failure of some kind. We will go over these sounds and
the repairs needed to fix the problem. The starter is a high torque electric motor fitted with a small gear and a
mechanism called a bendix. This small gear engages with the large gear called a
ring gear on the flywheel (standard transmission) or flex plate (automatic
transmission). The small gear contacts the large gear
only when the starter is engaged and then retracts after the engine starts. The solenoid is an electromagnetic switch and lever that throws the small gear
outward into the flywheel while turning the starter motor on. If the solenoid fails it will
not push the bendix gear completely into the flywheel which then creates a
grinding noise which means the bendix is not working and the
must be replaced.
Once the starter has been removed check the flex plate or flywheel condition.
This means observing the teeth of the ring gear which contacts the pinion gear
of the starter. If teeth are missing or badly worn
the flywheel must be replaced
before installing the new starter. Below is a picture of the flywheel on the
rear of the engine with the transmission being removed.
Flywheel Replacement Video6. Move the Gear Shifter to Neutral or Fully Depress the Clutch Pedal
Vehicles equipped with automatic transmission are designed with a neutral
safety switch that will not allow the engine to crank over if the gear selector
is not in park or neutral. For standard transmissions the switch is designed to
detect if the clutch pedal is fully depressed. This safety feature will not
allow the engine to start while the transmission is in gear which will make the car take off unexpectedly when the engine starts. Both of these switches are subject to wear and can become misadjusted or
have an open circuit due to time and usage. Furthermore if the clutch pedal is
not fully depressed due to a floor mat that has become lodged under the pedal or
the gear shifter on the automatic transmission is loose or broken the starter will not operate. Check to see if the floor mat has become lodged under the clutch pedal and
reposition it out of the way to allow full travel of the pedal. For automatic
transmission cars move the gear shifter to the neutral position and recheck the
operation. If the starter then works the
neutral safety switch has gone bad and needs
adjustment or replacement.
7. Mechanical Breakdown
If the starter makes a single clunk noise and then nothing it might be working
fine. The problem could be the engine is not allowing it to work because it
cannot be turned over due to a mechanical failure of some kind. To start
remove the serpentine belt and check to see if each of an accessory such as the
air conditioner compressor and
power steering pump spin freely and are not locked up not allowing the engine to
turn via the serpentine belt the try the starter. If the engine will still not turn over, check for internal mechanical failures which can stop the
engine from rotating such as a spun rod or crankshaft bearing, broken piston or
rod, dropped intake or exhaust valve or a
gasket. The easiest way to do this is to see if you can manually turn the
engine over by hand. Check for this problem by installing a large wrench or
socket with a long handle fitted onto the front crankshaft bolt and try to move
the engine clockwise. It should be difficult but not impossible to turn. If the
engine is locked up it will need to be replaced or repaired.