Top 6 Reasons My Car Starts Sometimes, and Sometimes It Doesn’t
Chris is Head of Content for FindTheBestCarPrice and is based out of Philadelphia, PA. As a seasoned automotive industry analyst and car enthusiast, he ensures the highest level of quality across all our content and curates our picks for the best deals each month.
Chris studied information systems and marketing at Drexel University and writes about a wide range of topics ranging from car buying tips to troubleshooting common mechanical issues.
When he’s not thinking about cars, he likes to stay in with his dog and make an “attempt” to finish a crossword puzzle (he’s not quite at the Saturday/Sunday level…yet). As a former cheesemonger, Chris still has a “sharp” passion for all things cheese, and his fridge is always loaded with it!
Chris also has a passion for things that go fast, and drones are no exception. He spends some of his time writing for Dronesourced.
If you've ever experienced the frustration of a car that starts sometimes and sometimes doesn't, you know how stressful it can be. This issue can be caused by a number of factors, ranging from a dead battery to a faulty starter motor.
It can be difficult to diagnose the problem without professional help, but there are some steps you can take to troubleshoot the issue on your own.
In this article, we will explore the common causes of a car that starts sometimes and sometimes doesn't, including problems with the battery, fuel filter, starter motor, and ignition switch. We will also provide tips on how to diagnose the issue and what steps you can take to fix it.
Whether you're a seasoned mechanic or a novice car owner, read on to learn more about how to deal with a car that starts sometimes and sometimes doesn't.
Let’s get started!
Table of Contents
Why Does My Car Start Sometimes and Sometimes It Doesn’t?
There are several compelling reasons why a car might suffer from intermittent starting. It could be an electrical issue, engine, starter motor, faulty fuel filter, et cetera.
The following are the usual causes of a car starting sometimes and at other times, it doesn’t:
1. Engine
There are several engine-related reasons why your car starts sometimes and sometimes doesn’t. They’ll be addressed below.
Engine Flywheel
The flywheel, an integral component positioned betwixt the engine and transmission, propels the engine by rotating the pinion gear.
The starter motor must be extracted to scrutinize the mechanics, the transmission must be placed in neutral mode and the crankshaft revolved.
The crux of the issue likely emanates from the pulley, which may trigger complications with the alternator or serpentine belt.
In addition, the flywheel’s absence or damage to teeth could account for the intermittent engine ignition.
Engine Ignition Coils
Malfunctioning engine ignition coils can likewise contribute to the predicament of sporadic engine ignition in my vehicle.
The ignition coil is pivotal in transmitting power to an internal combustion engine. With it, the electricity required to energize the spark plugs and commence vehicle operation would be attainable.
2. Starter Motor
Regarding the starter motor, below are the reasons why your car starts sometimes and sometimes doesn’t.
Bad Ignition Key
Certain automobiles are equipped with a key fob that comprises a battery, facilitating the communication between the key fob’s chip and the vehicle’s computer.
Occasionally, the identity chip embedded in the key fob fails to establish contact with the vehicle’s computer, leading to ignition failure.
Nevertheless, if the key is inserted and left in for a few seconds before ignition, the car will eventually start, a technique that numerous users have successfully employed. Thus, it is plausible that the root of the issue is the key itself.
The Starter Solenoid
The engine bay may generate a repetitive clicking sound attributable to a defective solenoid.
Furthermore, a loud clamor from beneath the hood indicates a lodged object hindering the engagement of the magnetic coil.
Should any of these sounds occur when trying to start the car, it could signify a defective starter solenoid that precludes the proper operation of the starting system.
It is essential to verify that the starter solenoid is securely connected and that the wires are devoid of contamination to facilitate the optimal functioning of the starting system.
Motor
A faulty starter motor can sometimes lead to a car starting sometimes, and other times it doesn’t. An audible grinding noise emanating from the starter motor often implies that the mounting bolts are inadequately secured, impeding the proper rotation of the flywheel.
It is crucial to tighten the bolts to guarantee the optimal operation of all motor components.
The mounting bolts may be tightly fastened in certain instances, yet the car still experiences intermittent starting difficulties. This predicament may result from the flywheel’s inability to rotate the motor to the requisite level.
To corroborate this assertion, one can examine the motion of the apparatus by rotating the pinion gear and assessing the movement for any anomalies.
3. Electrical Issues
Below are the electrical issues relating to why your car starts sometimes and sometimes it doesn’t.
Crankshaft Positioning Sensor
The crankshaft positioning sensor represents the foremost plausible culprit when confronted with intermittent engine ignition. In the event of its malfunction, the vehicle is rendered inoperable.
Preliminary sensor functionality results in prolonged engine cranking before ignition is achieved.
Diagnostic resolution of this complication is feasible by deploying an OBD2 scanner tool.
Nevertheless, even if the sensor appears to operate intermittently, subsequent vehicle movement cannot preclude the likelihood of battery damage.
4. Battery Issues
Below are the battery-related issues why your car starts sometimes, and sometimes it doesn’t.
Wires and Cables
The obstruction of the electric current due to damaged cables or wires can impede the ignition process and lead to the vehicle having starting problems.
This can manifest in corroded battery terminals, loose or broken connections, or faulty wiring.
Neglecting to conduct routine mechanical inspections can exacerbate these symptoms and increase the likelihood of experiencing difficulties with starting your vehicle.
Furthermore, the accumulation of dirt or debris can interfere with the proper functioning of battery terminals. One can alleviate this issue by cleaning the battery with warm water and baking soda.
While doing so, ensuring the solution does not come into contact with other components beneath the filler caps is imperative.
The Battery Voltage
Insufficient battery voltage is another plausible explanation for the intermittent starting issue of a vehicle.
It is imperative to ascertain that the battery possesses ample power to activate the engine. Employing a voltmeter, you can assess and gauge the battery’s voltage output.
It is recommended that the voltage range of the battery should be between 12.4 and 12.6 volts to initiate the engine successfully.
If the voltage value falls short of 12.4 volts, it is advisable to recharge the battery and retry starting the engine to observe if the issue has been resolved.
5. Fuel Filter
Here are the possible fuel filter issues relating to why your car starts sometimes and sometimes it doesn’t.
Contaminated Fuel Filter
A clogged fuel filter may hinder fuel flow into the engine, leading to difficulty starting the vehicle.
As a result, the fuel pump needs to generate more pressure to force fuel through the obstructed filter, which can overwork and ultimately damage the pump. This can cause the “car sometimes starts and sometimes doesn’t” issue.
The Fuel Injectors
The fuel injector is a pivotal component in the fuel filtration system, as it delivers fuel to the engine. If the fuel dispersion is not at the optimal pressure level, it can cause issues starting the vehicle.
Moreover, when the injectors are subject to direct damage, it can significantly impede fuel delivery to the engine, ultimately resulting in difficulties starting the car.
Faulty Fuel Pump
The transitory operation of the fuel pump occurs upon ignition key activation to create fuel pressure in the fuel line.
Observe the whirring noise from the pump during engine cranking to identify a faulty fuel pump. If the sound is absent, this signifies a malfunctioning fuel pump.
To confirm the diagnosis, test the fuel injectors, as they could intermittently inject fuel due to clogging or a faulty fuel pump.
In Gasoline Direct Injection Engines (GDI), an additional mechanically operated high-pressure fuel pump, the “high-pressure fuel pump,” is present.
Before removing the electrical fuel pump situated closer to the gas tank, it is advisable to examine the fuel pump relay and fuse of the fuel pump.
The fuel pump relay is typically housed within the fuse box, necessitating the review of the car model’s fuse box layout to locate the exact position.
While someone cranks the engine, listen for the whirring noise of the fuel pump. If you don’t hear any noise, it suggests that the fuel pump is malfunctioning.
You can test this by spraying some starter fluid in the air intake manifold and attempting to start the engine. If the engine starts quickly, the fuel pump is not working, or the fuel injectors are clogged, causing intermittent fuel injection.
In Gasoline Direct Injection Engines (GDI), the camshaft mechanically operates a high-pressure fuel pump.
Before removing the electrical fuel pump closer to the gas tank, check the fuel pump relay and the fuel pump fuse.
The fuel pump relay is typically situated in the fuse box, and you should refer to the fuse box layout of your car model to locate the exact position.
6. Engine-Related Problems
In addition to electrical and fuel delivery issues, problems with the engine can also contribute to intermittent starting problems with a vehicle.
Insufficient engine compression can lead to power loss and make starting the engine more difficult as the engine gradually loses power. To diagnose engine compression issues, a compression tester is required. Adequate compression for proper cylinder operation ranges from 90 to 100. If the result is below 90, the engine must be opened and inspected.
It is a relatively simple fix if the issue concerns valve problems. However, if the problem is more profound, more extensive analysis and repair may be necessary.
What to Do If Your Car Starts Sometimes and Sometimes It Doesn’t
When confronted with a car that starts inconsistently, examining if an OBD2 code is saved in the engine’s memory as the primary step is recommended.
The engine control module (ECM) generates Onboard Diagnostic (OBD2) trouble codes that help identify the flawed element in the engine, provided that your vehicle model is manufactured post-1996.
OBD2 trouble codes contain “PXXX,” with “P” indicating the engine’s powertrain. If the initial digit following “P” is “0,” the trouble code applies to all vehicles, regardless of the manufacturer. If it begins with “1,” the OBD2 code only applies to your vehicle.
For instance, the P1450 code is solely displayed in Ford vehicles. Conversely, the P0171 code carries the same significance for every vehicle.
To check if an OBD2 code is stored in the engine’s memory and causing the sporadic start-up issue, an OBD2 scan tool is required.
Bluedriver is my preferred OBD2 scan tool that can connect to a smartphone (Android and iPhone) via Bluetooth. Connect the tool to the OBD2 port of your vehicle and your phone. It will exhibit any stored trouble codes (if any) in your vehicle.
It is essential to recognize two types of intermittently starting car conditions. The first is the “crank, no start,” where the starter motor is active, and you can hear the motion, but the engine fails to start.
The second is “no crank, clicking,” in which you may hear one or more clicks or nothing when you turn the key.
