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Car cranks but won’t start because of ignition or fuel system defects. It will also fail to start due to engine flooding, electrical faults, or damaged sensors. This guide covers everything you need to know if your car cranks but won’t start.
Read on to find out how to detect and fix these issues.
JUMP TO TOPIC
- 1 Why Does a Vehicle Crank but Fails to Start? (10 Reasons)
- 1.1 Gasoline Flooding the Car Engine
- 1.2 Dirty or Clogged Fuel Filters or Injectors
- 1.3 Defects in the Fuses or Relays
- 1.4 A Dying Battery or Failing Starter Motor
- 1.5 Poor Fuel Supply Due To Bad Fuel Pumps
- 1.6 Problems With Engine Associated Sensors
- 1.7 Dirty Throttle Body Creates Problems After Battery Replacement
- 1.8 Lack of Ignition Due To Failing Spark Plugs
- 1.9 Defective Ignition Coil Pack in Old Car
- 1.10 Car Doesn’t Start Due to False Engine Timing
- 2 How Do You Fix a Vehicle That Cranks but Will Not Start?
Why Does a Vehicle Crank but Fails to Start? (10 Reasons)
A vehicle cranks but fails to start because of engine flooding, clogged or damaged fuel system components, or electrical problems. It can also happen due to a failing motor, battery, sensor, or ignition system component. Moreover, you can suspect false ignition timing or a dirty throttle body.
Gasoline Flooding the Car Engine
Most high-mileage cars fail to start or begin to stall due to a flooded engine. As a result, the spark plugs fail to ignite the fuel and air mixture. The gasoline washes off all oil on the piston rings and lowers compression.
Sometimes, you can resolve the issue by pressing the gas pedal. However, sometimes it becomes impossible to start the engine.
Gasoline usually floods the engine in cold because, in that case, the car needs more fuel to start. Once you start the engine and turn it off, the excess fuel floods the cylinders because it doesn’t get much time to evaporate. So a flooded engine explains your car turning over but not starting cold weather.
The problem also occurs if you idle the engine for a long time. The fuel pump keeps pumping the fuel even if the engine does not get the air to burn it.
Dirty or Clogged Fuel Filters or Injectors
If the starter works but engine won’t turn over, you might have clogged fuel injectors or filters. The problem occurs because the engine does not get the required fuel amount.
Having dirty injectors is a common problem. The nozzle of the injectors gets clogged with debris, rust, or corrosion particles. As a result, the injector fails to provide the correct fuel quantity to the engine cylinders, and ignition does not occur.
The injectors get clogged if you use poor-quality gasoline or last change the fuel a long time ago. Bad-quality fuel has debris or other sedimenting particles that gradually clog the injectors.
Moreover, dirty or substandard fuel also clogs the fuel filters. These filters lie in the middle of the fuel tank and pump to strain the impurities and keep them away from the combustion chamber.
If the filters get clogged over time, less fuel will enter the engine, and the engine will fail to power the car. So even though you might hear the engine crank, it will not start because of insufficient fuel.
Defects in the Fuses or Relays
You might have a burnt fuse or relay if your car struggles to start but battery is fine. Both components have safety purposes in the electrical systems. Your car has multiple fuses and relays covering each electrical circuit.
These components get burned or switched off in case of an electrical upsurge. The purpose is to protect essential or expensive electrical parts in the car. If a fuse burns, the current does not flow through the current.
You can check the fuse box to inspect their condition. It is a relatively easy repair mechanism; you can perform it without a mechanic. A damaged alternator can also create starting issues.
A Dying Battery or Failing Starter Motor
If you’re facing a situation where your car won’t start turns over but won’t catch, you can suspect a dying battery or a failing motor. Although most people believe every electrical system halts when the car battery fails, it’s not true.
The battery might fail gradually, allowing the engine to crank for a few days and completely shut down. The same is true for a starter motor. A failing motor is not powerful enough to start the engine. You can detect a fault in the motor if you hear odd noises with the cranking.
Poor Fuel Supply Due To Bad Fuel Pumps
The fuel pump forces the fuel from the tank into the engine. It does this with the help of a motor that creates suction to pull gasoline from the tank. Your car will fail to start if it has a faulty fuel pump.
The following issues lead to a damaged pump:
- Car accident or road impact
- Overheating due to lack of fuel
- Corrosion or debris accumulation due to substandard fuel
- Damaged relay or other electrical components in the pump
Problems With Engine Associated Sensors
You can rule out a dead battery when your car won’t start but all the lights come on, and suspect car sensors. Your car has different sensors with varying functions; the engine does not start if one fails.
For instance, your engine will display incorrect firing if it has a damaged crankshaft position sensor. This sensor ensures the spark occurs at the right time; otherwise, the engine will not burn the entire fuel.
A failing crankshaft sensor does not access the piston or valve positions, so the control unit does not know when to ignite. Moreover, a faulty camshaft sensor or a mass air flow sensor also prevents the car from starting. You can detect a faulty sensor by using a multimeter.
Dirty Throttle Body Creates Problems After Battery Replacement
If you have recently changed the battery, you might face issues starting the car due to a dirty throttle body. A dirty throttle body makes the throttle position sensor send false results to the control unit.
The problem does not get prominent unless you change the battery and restart. As the throttle gets dirty, the control engine adjusts its position by relearning. This relearned information gets erased when you change the battery and the car fails to start.
Lack of Ignition Due To Failing Spark Plugs
The car cranks but wont start even with starting fluid if you have bad spark plugs. The spark plugs are essential engine components that provide the spark to ignite the fuel and air mixture.
Although they should last long, premature damage can create engine starting issues. A common reason is carbon buildup or oil leaking into the engine. However, you can easily detect this fault and get replacements without spending too much.
Defective Ignition Coil Pack in Old Car
Old car models used to have ignition packs instead of ignition coils. These packs lie near the engine, but sometimes, they are in the trunk or under the hood. They get corroded or damaged after you wash the engine or drive in the rain.
Some cars have separate ignition coils for all cylinders. Although not very common, you may face the same starting issue if the ignition coils get damaged.
Car Doesn’t Start Due to False Engine Timing
Your car may have false engine timing if you have recently changed the timing belt or chain. The timing belt joins the camshaft and crankshaft and ensures valves open and close synchronizing.
A failing timing chain may skip a tooth and result in disastrous engine damage, such as a blown head gasket. Therefore, you should get it checked at least every 4 to 5 years.
The belt loses the tooth due to a faulty tensioner or lack of engine oil. The valves can also bend if the chain skips at a high speed. Hiring a professional to examine the timing belt will be best.
How Do You Fix a Vehicle That Cranks but Will Not Start?
To fix a vehicle that cranks but will not start, you can use an OBD scanner to find the fault. You can recharge or replace the battery if it’s causing the problem. You can also restore the correct fuel pressure by repairing the damaged parts.
Scan the Trouble Codes To Find the Problem
If the engine cranks, but the car won’t start, you must first scan the vehicle to find the trouble codes. Sometimes, a warning light on the dashboard, such as a check engine light, indicates the problem. However, you should use a code scanner to know what’s wrong with the car.
Attach an OBD scanner to your car’s port near the steering wheel. The scanner will take a while to show the codes. Once you get the code, look it up online to know the problem.
You can also take your car to an auto repair shop and have them scan it. Once diagnosed, you can fix the minor issues yourself. These include replacing a blown fuse, a bad starter, or a bad ignition switch.
Charge or Replace the Failing Battery
You can charge or replace a bad battery if the scanner does not show a code, and you’re wondering, “What do you do if your car cranks but won’t start?” Start by inspecting the battery connections.
You’ll have to clean the battery terminals if you see corrosion. You can mix water with baking soda and apply it to the corroded areas. Wipe it off later with a paper towel.
Here’s how you can determine if you need to charge the battery:
- Turn off the car and its accessories.
- Get a multimeter and set it to 20V DC.
- Connect the red lead on your multimeter to the positive battery terminal.
- Connect the black lead on your multimeter to the negative battery terminal.
- Charge the battery if the measurement is lower than 12.4 volts.
See if the car starts after charging. If the problem persists, perform a cranking test to inspect the battery. Here’s how you can do it:
- Turn off the vehicle and associated accessories.
- Disable the ignition so the engine cranks but does not start.
- Connect a multimeter and use it the same way as above.
- Ask someone to turn on the ignition for 15 seconds. Meanwhile, you have to watch the multimeter.
- If the voltage is less than 9.6 volts, your battery is powerless and needs replacement.
Fix Spark Issues To Restore Ignition
You might need to change the spark plugs if your car won’t turn but the engine cranks. Here’s how you can detect faulty plugs:
- Let the engine cool down and take off its cover.
- Find the plugs on top of the motor in 4 or 6-cylinder engines. Some cars have cylinders on both sides of the engine to help you understand your vehicle before looking for the plugs.
- Remove the injectors to prevent the engine from flooding.
- Remove the spark coils from the plugs that you want to test. You don’t have to remove them from the wiring harness.
- Connect your spark plug tester to the coil and plug and turn it on.
- Meanwhile, ask someone to turn the ignition and crank the engine.
- If there’s no spark, the tester will not respond while the engine turns.
You can purchase new plugs and replace the old ones at an economical price. You can also test and replace the coils if you detect bad ignition coils.
Ensure a Suitable Fuel Pressure
Your code scanner might tell you about low fuel pressure if it’s an advanced device. However, you can also use a pressure gauge to analyze the fuel pressure. If it shows low pressure, you must pinpoint the exact fault in the fuel injection system.
If your car doesn’t start due to a minor fault, such as clogged filters, you can clean them yourself. You’ll need to hire a mechanic for severe issues such as a damaged pump. You can create a crank no start checklist to inspect and rule out the functioning fuel system parts.
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