Car Repair and Maintenance

20 Reasons Car Struggles to Start But Runs Fine [Quick Fix]

This post reveals why your car struggles to start but runs fine, and, of course, we include the possible fix needed to get the car performing well again.

When facing this problem, you would notice that the engine cranks for a while when starting. The hard part is the embarrassment, especially if you are traveling with someone or blocking the traffic.

Although the mechanic is the right professional the vehicle needs, this article helps you determine the possible problem. And in the event of visible damage, you replace it yourself to fix the problem.

Read also: why an automatic car will stall in reverse

car struggles to start but runs fine

Oil and gas Problems

You may think you have enough fuel, but looking at the fuel meter may show you are running out of gas. The oil you use may be contaminated, so the car struggles to start but runs fine afterward.

Let’s the some possible in this category:

  • Previous oil interference

Not changing your car oil often will leave oil residue that can gradually thicken, which thickens the flow to the engine.

How to fix

The solution, in this case, is to regularly change the oil filter to prevent your car from struggling when starting.

  • Fuel consumption due to weather

Cold weather negatively affects the fuel economy of a car.  The U.S. Department of Energy’s fuel economy tests indicates that standard gas mileage is about 15% lower at 20°F than at 77°F due to cold weather.

How to fix

Certain fuels are weather-specific, so buy suitable fuel for your car.

  • Gas contamination

Air can contaminate gas. For example, microorganisms pollutant particles. Even water contains sediments and rust, which can contaminate gas.

How to fix

The simple fix for this problem is to inspect your fuel content regularly – weekly or monthly.

Make sure to buy good quality fuel to avoid low-quality fuel with much water or alcohol containing even less fuel, which disrupts chemical combustion. Meanwhile, here is how to convert gasoline car to alcohol.

  • Weather problem

Too cold or too hot weather will cause a car to struggle to start. Cold weather will cause your car oil to thicken, which prevents smooth flow, adding pressure to the battery.

Hot weather conditions can lead to the evaporation of liquid electrolytes, causing power inefficiency, and the car will take time to start.

Fuel pressure

Another reason car struggles to start but runs fine afterwards is Low fuel pressure. And this could be a result of low fuel in the gas tank and other factors considered in this section.

  • Bad fuel pump

The fuel pump supplies the fuel needed to run the car. However, it can be affected by factors such as cold weather, which reduces the engine supply. This typically causes the hard start you get, even though the car runs fine, because the pump needs to heat.

A fuel pump requires suitable voltage to move enough fuel to the engine to start. A low voltage means malfunctioning pumping, and the battery power could cause this. As such, this problem is linked to the car battery.

  • Dirty or broken fuel filter

The fuel filter collects debris and dirt in the fuel that can interrupt the chemical reaction or, in extreme cases, damage the engine. A clogged filter will also cause low pressure.

How to fix

Clean the fuel filter. If broken, you need a replacement fuel filter for your vehicle model.

You also want to know why the filter goes bad. Check the fuel quality, and consider a change of fuel if this is the reason for the bad filter.

  • Fuel injectors

The fuel injector in a car is an electronically controlled valve responsible for receiving pressurized gasoline from the fuel pump.

Fuel atomizes into a fine mist when it receives sufficient energy, which makes it easier to burn in the engine.

A failing fuel injector restricts the high spray of fine mist. Unfortunately, this causes a drop in the engine’s ability to burn fuel. This will happen if carbon contamination stops the valve from closing.

You would also experience an oil leak since the fuel reaching the engine for ignition is insufficient when you start the car. Thus, the car struggles to start but will run fine when it starts.

  • Failing fuel lines

The fuel lines move fuel from the tanks to the engines and can cause a car to struggle to start if damaged.

Fuel lines typically rub against metal and tend to wear gradually, causing low pressure and cutting proper fuel supply.

Starter motor

A starter motor not connected to the flywheel is another reason a car struggles to start but runs fine afterwards. The motor fails to spin as a result. And since it is required to start the car, you would have to struggle to fire the engine for some time.

The car battery powers the motor, helps to start the engine, and is connected by the motor relay. If any of these two components is faulty, your car will have a hard time to start but will run normally.

Bad motor could be a result of:

  • Wire leaks
  • Relay problem
  • Loose battery and motor wiring
  • Starter system problems
  • Oil leak
  • Motor burnout from low voltage

Related starter motor problems include:

  • Worn solenoid

The solenoid is a coiled cylindrical component connecting the power from the battery to the starter motor. If worn, the car struggles to start but will runs fine when it eventually starts.

How to fix

The solution is to replace the solenoid.

  • Worn ignition coil

The function of the ignition coil is to transform battery voltage into electrical energy. It also provides spark plugs to ignite fuel.

A worn ignition coil restricts sufficient transformation, reducing the sparks produced for fuel and air mixture combustion. Energy transportation is typically relaxed when the ignition coil fails. This stops spark plugs from getting sufficient power and sparks firing the fuel mixture.


Buy the manufacturer-recommended ignition coil replacement. Have the mechanic determine if this is the cause of the problem.

  • Torn coil

Tears in the coil prevent the transformation and transportation of the necessary energy. The solution is to have them replaced.

  • Bad ignition switch

The ignition switch is another reason a car struggles to start but runs fine afterwards. When broken, the ignition switch no longer supplies power to the starter motor and other engine components needed to start the car.

This also stops the switch from starting the engine, so you have to start the car many times to power the engine.

How to fix

You can fix this problem by finding out why the ignition switch is worn. This could be due to attaching the heavy keys in the ignition for too long. Have it replaced to start the car smoothly.

  • Spark plugs and incorrect ignition timing

Insufficient sparks for fuel and air mixture to ignite is another primary reason a car struggles to start but runs fine afterwards.

The ignition coil needs to output more energy to compensate for the damage, which overheats the coil to fail. Thus, enough energy is generated to start the car.

Spark plugs contain electrodes that gradually wear. This increases the gap. Thus, a large voltage of current is required for the reaction.

Ignition timing is when the fuel ignition begins as you start the car. If the timing is incorrect, the sparks fire too quickly or too late. As a result, the fuel and air mixture will burn improperly, causing the engine a hard start time.

How to fix

Inspect the spark plugs when checking the ignition coil. If the spark plugs are worn off or the gap between the plugs is wide, get replacement spark plugs.

Damaged distributor cap and motor

The distributor cap is responsible transports electrical energy from the ignition coil to the engine cylinders for the engine to ignite. Reasons the distributor cap will cause your car to take time to start include:

  • Moisture

Moistures on the cap, alongside other foreign objects like dust and pollutants, can clog the distributor cap. This will keep the distributor cap from transporting sufficient energy to the cylinders, causing a squeak in the engine and taking longer to start.

How to fix

Get rid of water and other foreign substances from the distributor cap.

  • Wear and tear

The location of the distributor cap is exposed, so it will wear and tear. The rotor on the cap transfers high voltages to the right spark plugs and cylinder.

Thus, maintaining voltage precision and timing is crucial, and can wear out the distributor cap and rotor.

Clogged air filter

The function of the air filter is to supply oxygen to the car for the combustion process. This filter also prevents dirt, debris, pollutants, and dirt from entering the engine.

If the air filter is clogged with dirt, debris, and other foreign substances, your car will struggle to start since there is a reduced amount of oxygen getting to the engine which also causes slow combustion. However, the vehicle will operate fine.

The combustion can sometimes be incomplete, accumulating soot in the spark plugs. Since the spark plugs cannot generate and supply enough sparks to the engine, the car will take longer to start.

Charging systems

When a car struggles to start but runs fine afterwards, it could be a charging system problem. This section will consider causes such as the battery, alternator, wiring and relays.

  • Failing car battery

Under the charging system, we will first consider a faulty battery as the reason your vehicle struggles to start but runs fine when it starts.

If you recently had battery issues, the battery could likely be the culprit. A failing battery has no power to supply the charge needed by the battery, making it harder to start the engine.

Your car’s electrical system relies on the battery power and voltage. Thus, electrical systems, fuel pumps, and even starter motors will not get the required power to run.

How to fix

The first fix is to charge the battery. Consider jumping the car battery by pushing or use jumper cables if no charging equipment is available.

Terminal corrosion could also be why the car battery makes it tougher to start the car. Inspect the battery terminals for corrosion. If corroded, disconnect the cables and clean the area using a brush. Tighten the cable’s wires firmly when done.

Loose wire connections can also be the reason the battery gives a hard start. Ensure to tighten the connections.

Lastly, you may have to replace the battery if it is badly damaged. Battery wears over time and would cause a slower start when degraded.

  • Failing alternator

The alternator charges the car battery and generates the spark needed to start the engine. Thus, if your car struggles to start but runs fine, the alternator may be failing to sufficiently charge the battery.

How to fix

The simple fix here is to get a replacement alternator. Typically, you would find yourself having to jump the car too often, which is not always good.

  • Broken drive belts

The vehicle drive belts can be the reason it takes longer for your car to start but runs okay when it starts. A loose drive belt will cause a charging system delay, so the car battery does not receive sufficient charging power.

  • Wiring problem

The vehicle wiring system transmits power across components. If failing, the battery no longer gets the correct connection with the alternator, which causes a car struggles to start but runs fine afterwards.

How to fix

The solution is to inspect the wiring and cables. If you detect corrosion or leakage, this could be the reason for your car struggling to start.

Your vehicle starter uses two wires you need to examine for corrosion and leaks. If corroded or leaking, brush and fix. You may have to repair the wiring systems if they are irreparable.

Broken timing belt

The timing belt helps open and shut off the car valves and keeps the internal combustion engine running.

If the timing belt misaligns, it stops running correctly, keeping the valves open, and the piston moves up and down unusually faster without resistance.

Occasionally, pulley belt damage rips the belt, causing it to operate unusually slower.

How to fix

The solution is to get a replacement belt to prevent potential damage to the engine. Ensure sure to align it properly during installation.


In conclusion, if a car struggles to start but runs fine afterwards, a few potential causes could be at play. It could be due to a weak battery, a faulty starter motor, a clogged fuel filter, or several other factors. A mechanic must diagnose the car to identify the root cause and address it promptly to avoid any further problems.

Neglecting the issue could lead to more severe damage to the engine or other components of the car. With proper diagnosis and repair, the vehicle should be able to start smoothly and operate as it should.


Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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