Engine starts but won’t stay running is usually caused by fuel delivery problems, faulty spark plugs, or air intake issues. Fixing components like the fuel filter or ignition system can resolve the issue.
Nobody likes dealing with car issues, and having a car that starts but won’t keep running is one of the worst problems a car owner can deal with. On top of everything, problems like these make people feel stuck and confused. They’re often not sure how to solve the problem. Identifying the problem is the first step to fixing the issue. The car having fuel issues, an ignition problem, or an issue with the air intake system are all problems that make a car start but not keep running. Understanding the exact issue can help you come up with a solution.
In this post, we will go over how to figure out which issue is the cause of the problem, and we will give you practical step to fix the problem yourself. Whether you’re seeking help from a mechanic or prefer to take on the task yourself, this guide will explain the issue and how to fix it.
Contents
What Does It Mean When the Engine Starts But Won’t Stay Running?
When an engine starts but won’t stay running, it means the engine is able to fire but is stalling or shutting down for some reason. This can occur within seconds or after the engine has been running for a little while. The point is, the engine’s management system is unable to maintain a steady idle, which is essential for keeping the engine running after it has been started.
There are multiple potential problems within the ignition, fuel, or air intake systems that can cause the engine to shut down after starting. The problem may be be short lasting, or it may be persistent, depending on the cause. In certain situations, it may just require a simple fix, but it can also be the case that a more serious component needs to be replaced. Fixing problems as soon as they are identified can help to avoid more serious problems with the engine.
Common Causes of an Engine Starting but Not Staying Running
There can be numerous reasons that lead to this problem, but let’s discuss some of the most common causes, and how they impact the performance of the engine.
Here are some fuel delivery problems that can lead to an engine stall:
1. Problems with Fuel Delivery
When it comes to engine stalling, one of the most common issues is fuel delivery. If fuel is not consistently delivered, then the engine will not be able to run. There are many systems involved in fuel delivery and any of them could be having issues. Some of the most common issues are:
- Blocked Fuel Filter: The fuel filter is designed to trap dirt, debris, and anything else that could damage the fuel injectors and the engine. Over time, the fuel filter itself can get dirty and start to limit the amount of fuel that can flow to the engine. If the engine is not able to get enough fuel, it may turn on, but it will stall afterwards. This is a common reason older vehicles stall, due to dirty fuel filters.
- Malfunctioning Fuel Pump: The fuel pump sends fuel from the gas tank to the engine. If the pump is not functioning, then the engine will not get the fuel that is needed to run consistently. If the fuel pump is weakening, it will cause low fuel pressure, which will lower the engine’s normal functioning. Dirty and Damaged Fuel Injectors
- Dirty or Faulty Fuel Injectors: The fuel injectors are supposed to provide the exact amount of fuel needed for the combustion chambers in the engine. If they become clogged or damaged, they could provide too much or too little fuel. This could cause the engine to run rough or stall altogether. Fuel injectors will become dirty, and this will create problems in the flow of fuel.
2. Issues with an Ignition System
An ignition system is the most fundamental system of a vehicle engine because it directly correlates with the start of the engine and the continuation of its operation. Thus, if there is a malfunction with any component of the ignition system, then the engine will fail to run properly and will fail to continue running. Below is a list of vital components of an ignition system that are most likely to be the cause of a malfunction.
- Malfunctioning of a Spark Plug: All the internal combustion engines are designed to have spark plugs that create a spark to ignite the fuel and air mixture in the engine’s combustion cylinders. Thus, if the spark plugs are not functional, they will not be able to create a spark which is then needed to maintain the engine operation. As a result, the engine may start and then stall almost immediately. Spark plugs which are worn out are likely to also cause ignition failures(called misfires) and are likely to lead to excessive fuel consumption.
- Malfunctioning Ignition Coils: Ignition coils supply electricity to spark plugs, which means that faulty coils could leave spark plugs without the energy they need to create a spark, leading to unburned fuel, misfires, and stalling. Most of the time, issues like these can be solved by replacing an ignition coil.
- Faulty Crankshaft or Camshaft Position Sensors: Crankshaft and camshaft position sensors detect the position of the crankshaft and camshaft respectively, and send that information to the ECU. A malfunctioning sensor could disrupt the ECU from communicating properly to the ignition system, resulting in engine stalling. The camshaft sensor will also determine the timing of fuel injection, and the crankshaft sensor will determine the timing of the ignition.
3. Problems with Air Intake Systems
For the engine to run well, it must achieve the best air-fuel mixture possible. Problems with the air intake system may cause the engine to have problems staying idled, or it may even cause the engine to stall after it has started. The following factors may constitute problems with air intake.
- Air Filter Can Become Clogged: The air filter ensures that the air entering the engine is free from impurities such as dust, dirt, and other solid matter. When the air filter becomes clogged, it reduces the amount of air available to the engine, and as such, it will impact the mixture of air and fuel that the engine will have available. Clogging of air filters will make it hard for an engine to have an idle and may also cause an engine to stall after it has just been started.
- The Mass Air Flow (MAF) Sensor Is Dirty or Failed: The MAF sensor’s job is to detect the volume of the air that is entering the engine, and it relays that information to the engine control unit (ECU). The ECU will then make modifications to the volume of fuel being injected into the engine. When the MAF is dirty or defective, it may cause the engine to have wrong readouts which in turn will yield a bad air-fuel mixture which may cause stalling. MAF sensors may be cleaned if dirty, but defective MAF sensors may necessitate a change of the whole sensor.
- Vacuum Leaks: Vacuum leaks are when air interrupts engine fuel and air mixes by sneaking into the intake system. When this happens, the engine runs while stalling. Things causing vacuum leaks are cracked vacuum hoses, leaking intake manifolds, or faulty gaskets.
4. Engine Control Unit (ECU) Malfunction
The ECU controls different segments of an engine. An ECU malfunction can cause the engine to turn over and stop. Having issues with an ECU is uncommon but can be tricky to figure out, as the right equipment is needed. If everything else looks good, an ECU is likely the problem.
5. Bad Idle Air Control Valve (IACV)
The IACV controls how much air goes into the engine when the throttle is closed and keeps the engine idle speed consistent. When the IACV is dirty or breaks, the engine may not have a consistent idle speed which can cause the engine to stall after starting. The problem can be fixed by cleaning or replacing the IACV which would allow the engine to idle smoothly.
Diagnosing the Problem
Here, we will cover multiple steps required to check an engine to stay troubleshooting.
- Checking for Diagnostic Trouble Codes: Look for possible trouble codes. Trouble codes can tell us which systems or components are causing an issue, which can help us determine the areas we should focus our investigation.
- Examine the Fuel System: Before moving on, check the fuel filter for any blockages. If the filter, test the fuel pump to see if it functioning and if it is supplying fuel. If the pump is weak, it may need replaced. If the fuel injectors are weak, they may need replaced.
- Examine the Ignition System: Examine the spark plugs for any damages. If the plugs show signs of a build up, they should be replaced. If the ignition coil is faulty, it should be replaced. Check the crankshaft position sensors and replace them if needed.
- Air Intake System Components: Start by checking the air filter and cleaning or replacing it if it is dirty. Check the mass air flow (MAF) sensor for dirt and damage. If the sensor is dirty, clean it. If it is faulty, replace it. Check for vacuum leaks and replace damaged hoses or seals.
- Idle Air Control Valve (IACV): Check the IACV for dirt or build-up and clean it if necessary. If the valve is faulty, it may need to be replaced.
Solutions to Fix the Problem
After you’ve diagnosed the problem, the solutions will vary depending on the problem.
- Fuel Filter or Pump Replacement: If the filter is causing the engine to stall due to clogs, the filter will need to be changed. The pump will need to be changed if it is failing to ensure proper fuel delivery.
- Cleaning or Replacing Spark Plugs: If the spark plugs are worn or dirty, replace them. If they are simply dirty, cleaning them should suffice.
- Replacing Ignition Coil or Sensors: If the ignition coil or the position sensors are faulty, replacing them should fix the issue.
- Cleaning or Replacement of MAF sensor and Air Filter: Cleaning or replacing the MAF sensor can fix the air-fuel mix issue. Air filter needs replacing too if it is dirty.
- IACV Needs Cleaning or Replacement: To restore normal idle speed and avoid stalling, the IACV needs to be cleaning or replaced.
When to Get Professional Help
If the steps are done and still the engine is not running, or if the repairs are too much to handle, calling a mechanic maybe the best option. Mechanics can be able to find the problems using sophisticated tools and fix the issues.
Frequently Asked Questions
Here are some FAQs about engine starts but wont stay running medium issue –
1. My car starts but and then immediately stalls, what is wrong?
Fuel system problems could be the burning cause. This includes a clogged fuel filter, a fuel pump that is failing, or dirty fuel injectors. It could also be problems in your ignition system, like bad spark plugs and ignition coils, which can also cause stalling.
2. Does a dirty air filter cause the engine to stall?
A clogged air filter restrict airflow, which can then cause the engine to stall.
3. How can I resolve an issue with fuel delivery?
You can always check and change the fuel filter. If faulty, the fuel pump and fuel injectors then should additionally be tested and replaced.
4. Why does my engine stall even after replacing the spark plugs?
Other issues are possible and could relate to the ignition coil, crankshaft/camshaft position sensors, or air intake system. Look into those possible faulty parts.
5. When should I consult a mechanic?
If you don’t feel comfortable working on it, or if you have gone through the troubleshooting steps and the issue is still unresolved, then you should have a mechanic look at it.
Conclusion
The causes for the running problems of the engine can be many and are usually a mix of problems of the fuel delivery, ignition system, air intake systems and even a malfunctioning ECU. For the right diagnosis, the fuel filter, spark plugs, ignition coil, and air intake system must be checked.
If you know what you’re doing, some of these can be repaired quite simply. If the issue is still there, or you aren’t comfortable doing the repairs, seeking a professional is always a good idea. This minimizes the chances of problems that can cause the engine to run more smoothly and more efficiently. Problems can be avoided by simply by doing regular vehicle maintenance, as well as, addressing problems as soon as you can.
