How to start a Car with a Bad Fuel Filter?

For brake fluid, coolant, and engine oil, purity is important. But for fuel, the fuel filter is as important as the entire fuel system. Whether you own a diesel or gasoline-powered vehicle, a bad fuel filter can cause several problems.

Car manufacturers install fuel filters in cars to filter contaminants and other impurities from the fuel that could cause severe damage to the engine. The filter is a maintenance item that needs to be changed from time to time. Failure to replace the fuel filter routinely will let it clog and cause potential issues that will affect vehicle fuel economy, reliability, and performance. It could prevent the car from starting.

In this article, I’ll explain how to start a car with a bad fuel filter, how to check a fuel filter, and signs you need to change your fuel filter.

how to start a car with a bad fuel filter

How do you check a fuel filter?

How to check a fuel filter is as simple as ABC. After removing the fuel filter, you can tell whether it is clogged or not by performing a simple blow test.

The first thing you should do when checking a fuel filter is to drain the fuel inside the filter. Drain as much fuel as you can. Find the inlet side of the fuel filter. It should be labeled “IN” or have an arrow that indicates how the fuel flows. Clean the inlet with a clean rag.

Drop the clean rag on your workbench and blow the fuel filter. Ensure the outlet is pointing to the rag on your bench. You should blow through without any resistance. If the filter is clogged, it will have much resistance to blow through.

If there’s no resistance, but the fuel coming out of the filter is dirty, it means the fuel filter is dirty and needs cleaning. In this case, all you have to do is pour more fuel into the filter, tap it with a metal, and shake it regularly. After that, blow the filter again.

Keep in mind you have to repeat this step three or four times before you will start seeing clean fuel. But if you want excellent results, you need to do something extra. Pour lacquer thinner into the filter or any good cleaner and let it sit for a minute before blowing it out. The result will amaze you.

The thing is, gasoline is gross, flammable, and it doesn’t taste good. So, you have to apply all precautionary measures. Allow the rag you used during the testing to dry before throwing it into the trash can.

How to start a car with a bad fuel filter?

You cannot start a car with a totally clogged fuel filter because it won’t allow fuel to get to the engine. A partially clogged filter will cause poor engine performance. But the car won’t start with a completely clogged filter. The only way to start a car with a clogged fuel filter is to clean or replace it.

Aside from a bad filter, several other factors can cause a car not to start. So, it is essential to isolate the fuel filter and ensure it is the reason your vehicle is not starting.

Here are impurities, contaminants, or water in fuel filter symptoms that will point to a bad fuel filter; Power loss when carrying a load, fuel pump quits, stalling or rough running, check engine light, bad gas mileage, car won’t start.

So if you are experiencing the above signs, here’s how to fix a clogged fuel filter and start your car.

Locate and check the fuel filter.

The first step is to locate the fuel filter and inspect it. The fuel filters are usually located underneath the vehicle or under the hood between the fuel tank and the fuel injectors. Before removing the filter, check the fuel pressure to see if it is enough to break the fuel pressure regulator.

A clogged fuel filter will reduce the fuel pressure so it won’t pass the fuel pressure regulator to start the engine. You can check the fuel pressure using a pressure gauge.

Clean or change the filter

If the test shows, the fuel pressure is low, clean or change the filter. After that, start the vehicle and see if it will start. You have successfully fixed the underlying issue if it starts and runs fine.

However, if the fuel pressure is still low even after replacing the filter, you should inspect the fuel pump. A bad fuel pump can also pose the same symptoms.

How to start car with bad fuel filter?

Frequently Asked Questions (FAQs)

Will your car start with a bad fuel filter?

Rarely will a clogged fuel filter cause a car not to start unless the filter is completely clogged. Before a fuel filter prevents a vehicle from starting, it must have given several signs like hard starting, engine stalling, and poor engine performance.

Can I drive with a clogged fuel filter?

While you can drive with a bad fuel filter, you may damage the fuel pump if you continue driving with it for an extended period. A clogged filter will put extra strain on the pump, making the pump motor work harder.

Imagine the pressure and effort you put in when blowing a completely clogged fuel filter. Yeah! That’s what the fuel pump suffers when driving with a bad filter.

Can a bad fuel filter cause engine overheating?

Generally, a bad fuel filter will restrict appropriate fuel flow to the engine. This means there will be more air than fuel in the combustion chamber, causing the engine to run lean. Since the engine running lean will increase the engine temperature, it is possible for a clogged filter to cause overheating. But trust me, this will rarely happen.

Can I clean a fuel filter?

Regardless of the type of fuel filter you have, it can be cleaned when it gets dirty. However, you should replace the filter if the accumulated dirt, impurities, and contaminants are too bad. This is because the dirt may have been there for long and will be too difficult to be removed.

Similarly, if you are asking, can a clogged fuel filter unclog itself? The short answer is it depends on the severity of the clog. If the clog is very small, the filter can unclog itself, but if it is much, you don’t have to wait for it to unclog itself because it never will.

Can a fuel filter cause a loss of power?

One of the common signs of a lousy fuel filter is decreased engine power. Overall, a loss of engine power, especially when accelerating, is caused by a clogged fuel filter. If the engine is not getting the required amount of fuel needed for optimal combustion, there will be reduced engine output.

What happens when the fuel filter is dirty?

A clogged fuel filter will restrict the engine from getting enough fuel for proper combustion. This will lead to hard starting, rough idling, engine stalling, vibrations, and loss of power, especially when accelerating. In a worse case, the vehicle won’t start.

Will a dirty fuel filter use more fuel?

Generally, a dirty fuel filter can restrict fuel flow into the engine, resulting in lean engine, misfires, poor gas mileage, hard starting, stalling, poor throttle response, and the check engine light on the dashboard.

Final Words

To sum it up, it is rare for a bad fuel filter to stop a car from starting, and when it does, the only way to start the vehicle is to clean or replace the fuel filter.

If you notice any sign of a bad fuel filter, it is time to replace it. You can also clean the filter with any of the best fuel filter cleaners on the market. Cleaning and replacing fuel filters are one of the most common car maintenance anyone can do.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

Recent Posts