Why Won’t My Toyota 4Runner Start?

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SUVs are often blamed for not having comfortable seats and an aesthetic interior. However, in the case of Toyota 4Runner, all such myths have been busted to a great extent.

An SUV that was launched in 10 different colors, the Toyota 4Runner stepped foot into the market back in 1985.

Despite being a versatile car, the Toyota 4Runner also has a high towing ability and an even better horsepower.

The Toyota 4Runner is a muscular car and is often praised for its strong engine, but there are instances when it fails to work.

This often leads to the users of this car wondering, “Why won’t my Toyota 4Runner start?”.

Through in-depth research on this matter, I have gathered five major reasons why your Toyota 4Runner would not start.

  1. Spilled Over Battery Acid
  2. Defects In The Alternator
  3. Impurities In Air Filter
  4. Clogged Fuel Filter
  5. Impact Of Rodents

The issues mentioned above are the main causes of why your Toyota 4Runner might fail to work, leading to the car not starting at all.

What Would Cause A Toyota 4Runner To Not Start?

Wondering why is your 4Runner not starting? Read my guide to find what reasons

Every car tends to experience several ups and downs, but that does not necessarily mean it is not a good car.

Technological advancements have helped us get out of every situation, and it will only get better.

There can be many reasons why your Toyota 4Runner would not start.

I have listed the most common reasons for this issue down below. Not only that but the ways you can cater to this situation have also been mentioned after every issue.

1: Spilled Over Battery Acid

Your car’s battery is necessary to provide it with the power or energy it needs to operate.

Not only that, but it also supplies electricity to your car’s electrical systems, like the audio and the power windows.

The battery in your automobile may become unable to work if rust accumulates.

You might need to remove corrosion from the battery if your Toyota 4Runner is not starting or if you detect issues with its electrical components.

Battery deterioration might cause other issues even if your car starts.

Battery acid spillover can completely ruin the outer body of the battery in your Toyota 4runner, reaching its internal components and damaging them too.

To understand how dangerous corrosion can be for your battery, it is important to know what it is first.

Battery corrosion appears as a white, green, or blue-tinged residue on your car’s battery’s wires, connectors, or cables.

Battery acid emits hydrogen gas, which interacts with the air and creates a corrosive atmosphere.

The battery can corrode in this atmosphere. Batteries are built with vent covers to release the explosive gases that battery acid can produce.

What Should You Do About It?

  • Cover your battery with battery grease. This would form a layer of protection for your battery. Any battery acid spillover will be prevented this way.
  • Make sure you have disconnected your battery and then spray anything that would prevent corrosion from taking place.
  • Take your car for daily maintenance checkups and ask the mechanic to carefully trace any signs of battery acid spillovers.

2: Defects In The Alternator

The alternator is one of your Toyota 4Runner’s most important engine parts.

Without a functioning alternator, your 4Runner’s battery won’t be capable of keeping the amenities and powertrain systems running for very long.

Before you are stranded somewhere, you should take care of any alternator issues you suspect you may have.

Regarding your automobile, truck, or SUV, the alternator is a crucial piece of equipment.

The alternator reuses the energy your car battery consumes while you’re driving, replenishing the energy it has lost and giving the electricity that the climate control, engine management, entertainment, and a variety of other systems require to function properly.

Your car uses a great deal of battery juice to operate. Without the alternator, the battery’s energy reserve would run out quickly.

Your car’s electrical system depends on an alternator that is functioning properly.

When the alternator has a problem or quits altogether, it may result in discomfort, pricey repairs, or even a breakdown.

What Should You Do About It?

  • Use a voltmeter to see how much voltage is sent to your car’s battery or engine through the alternator. If it is low than 12.65 Volts, then the alternator is malfunctioning.
  • Buying a new alternator can be too expensive. Rather you can consider purchasing a refurbished one. You will be able to find it at a good price.
  • If you are replacing the alternator yourself, at home, you disconnect the battery, or you can get electrocuted.

3: Impurities In Air Filter

An air filter can significantly improve your Toyota 4Runner’s performance.

Clean and properly installed air filters improve acceleration, fuel efficiency, and engine life while lowering pollutants.

When your air filters are clogged, your engine requires twice as much power. The air filter enables air to enter the engine.

For an internal combustion engine to operate, about 10,000 liters of air should be merged with each liter of fuel.

Without sufficient air admittance, the fuel mixture will be excessively fuel-rich and won’t burn efficiently; starving the engine of the oxygen it requires to function.

To understand this in-depth, your engine would fail to start if your air filter has been contaminated with impurities.

The air-fuel combination is altered as a result of the reduced airflow. The rich fuel mixture produces a black soot residue and coats the spark plugs.

The spark plugs’ improper firing causes the noise due to this residue. Dirty spark plugs might also contribute to misfiring and difficulty starting your car.

What Should You Do About It?

  • You must take your Toyota 4Runner to the service station every two months to clean the air filters.
  • Use a vacuum at home to suck all the impurities out of the air filter.
  • Get your air filter replaced once every 12 months. This would increase the performance of your car as well.

4: Clogged Fuel Filter

The fuel system wouldn’t function without a fuel filter. Gasoline filters ensure that the engine receives only clean fuel, devoid of debris, dirt, and other contaminants.

A gasoline filter protects the engine’s vital components throughout its lifespan by removing unwanted particles that can harm a fuel injector.

Fuel filtering involves a complicated procedure because many contaminants need to be removed.

Water and debris are the most frequent pollutants, which may do terrible things to your engine.

The fuel filter, if clogged, can cause your Toyota 4Runner to stop working. This is mainly because the engine requires a certain amount of fuel to operate efficiently.

When the fuel filter is clogged by water or debris, this causes the supply of fuel to decrease, and that directly impacts the performance of the engine.

Moreover, if the engine does not get the right type of fuel which is dust free and is of the right amount, the whole combustion process will not be able to start.

What Should You Do About It?

  • If the fuel filter has been contaminated by dirt, your first option is to use biocide on your car that fights microbial.
  • Use a solvent cleaner for your fuel filter if it is not made up of nylon or paper. This works best if your fuel filter is made up of metal.
  • Check for leakages in your car because if the fuel filter clogs the entire fuel supply, this can lead to certain outbursts and leakages.

5. Impact Of Rodents

Rats are usually found in sewers and garbage, but they also enjoy nesting inside automobiles during the cooler months.

They are drawn by the warmth and shelter but are entertained by the wires and hoses: Rats bite on objects to maintain their teeth because their teeth grow continuously.

They can spark fires, blow fuses, and even damage the components of cars inside an engine bay.

Many auto manufacturers now utilize soy-based wiring insulation, which is thought to be more environmentally friendly than the petroleum-derived coating it replaced, yet it is frequently criticized for this.

According to the complaints, rodent damage should be covered by car warranties, which claim that it is indeed sweeter to rats and hence defective.

What Should You Do About It?

  • Do not park your Toyota 4Runner outside, especially if trees surround your house. You need to park your car inside the garage.
  • The smell of food and debris smell attracts these rodents the most. When you leave the car, ensure you do not leave any food behind.
  • Steam cleaning is always a good option because it gets rid of the dirt and debris in your car and any small rodent inside your car.

Frequently Asked Questions

Q1. Why Won’t My Toyota 4Runner Start With New Battery?

If your battery is new, but your Toyota 4Runner is failing to start, then that suggests that the placement of the new battery is incorrect.

Make sure that all the wires and screws are put in place.

If you have not asked a skilled mechanic to place the new battery in your car, this would be the right time to do it.

Q2. Why Won’t My Toyota 4Runner Start Even With A Jump?

Toyota 4Runner might require a jump start only if the car’s battery is to be blamed for the engine not starting.

In other cases, giving a jump start to your car would not work. Your car might be facing issues in the alternator, or corrosion might have made its way inside the components.

Q3. Why Won’t My Toyota 4Runner Start But Lights Work?

If your Toyota 4Runner’s lights are working, you do not have to get your car’s electrical system checked.

This could have been an issue because every wire would have been checked. On the other hand, the issues discussed above, e.g., contaminated air filters, might be the reason.

Q4. Why Won’t My Toyota 4Runner Start But Cranks?

If your Toyota 4Runner cranks, the engine must be thoroughly checked. It might be getting a low voltage which can be checked using the voltmeter.

The issue might also be in the battery. Issues such as battery acid spillage or drained battery can cause this problem.

Q5. Why Won’t My Toyota 4Runner Start Just Clicks?

Clicking is worse than cranking!

This means that you can let the engine go and focus on more expensive to maintain components such as the ignition switch or the alternator of your Toyota 4Runner.

Moreover, you might have to get your car’s filters cleaned after hearing the clicking sound.

Q6. Why Won’t My Toyota 4Runner Start In The Cold Weather?

As discussed earlier, rodents tend to reside in car hoods because they consider that place warmer than most.

They also tend to then feed on the wires because of the sweet taste that they have.

Moreover, the chances of rusting are higher during cold weather, which can harm the car’s components. Make sure to check all these to solve the problem.

Q7. Why Won’t My Toyota 4Runner Start After I Get Gas?

The issues lie with an important component of the Toyota 4Runner: the fuel tank. From the fuel tank, issues in the fuel filter might also be brought into sight due to this.

While checking this out, make sure you locate leakages from below. Your engine is not getting enough energy or power to operate.

Q8. Why Won’t My Toyota 4Runner Start But Radio Works?

In this case, the main issue lies with your Toyota 4Runner’s ignition system. This system is responsible for sending power to the starter motor of the cars.

When this would not work, then the engine of the car would not work either. So, you need to get the ignition switch or coil checked and replaced.

Related: What Are The Worst Years For The Toyota 4Runner?


Every car formed by the most popular and renowned company, Toyota, has a different story.

However, what they all have in common is the fact that all cars tend to face issues now and then. I have tried to share most of the problems in this one.

Everything you need to know about “Why won’t my Toyota 4Runner start?” has been answered in great detail.

Go through this and follow the solutions that have been provided. All the solutions are tried and tested. These tend to provide the best results.