How to Clean a Clogged Fuel Pump (Step by Step Explained!)


How to Clean a Clogged Fuel Pump

Every gas-powered or diesel engine has a fuel pump, whether it is a car, marine, motorhome, or power generator.

Just like any other mechanical device, it can get broken. One of the most common problems of fuel pumps is clogging.

This is why it is important to know how to clean a clogged fuel pump. It is done very easily by replacing or cleaning the mash screen which catches almost all debris from the tank, and over time gets clogged.

Before getting on with the detailed step-by-step guide on fixing the clogged fuel pump, let’s discuss why the fuel pumps get clogged.

Why Does A Fuel Pump Get Clogged?

Fuel is a corrosive liquid, and it is stored in a metal tank. So, slowly over time, the rust will start appearing on the inside of the tank, no matter how much it is rust-proofed.

Also, the inside of the tank is warm, and microorganisms that can feed on complex carbohydrates from gas will flourish inside it.

That’s why fuel pumps have mash screens, but also the fuel systems have filters. Mash screen catches this debris, and over the years this buildup will clog it and the fuel can’t pass through it.

This you can recognize by its symptoms.

Read also >> Can a Clogged Fuel Filter Unclog Itself? (Full Guide)

Read also >> What Causes A Clogged Fuel Filter (Full Guide)

Symptoms Of Clogged Fuel Pump

A clogged fuel pump has similar symptoms to some other problems, your engine will be starting very roughly and need a lot of cranking.

Also, depressing the accelerator pedal will not produce a quick reaction from your engine as it used to. You can also notice that the RMPs sometimes fall without lifting the foot from the accelerator.

But, the most important symptom, which will tell you that it isn’t something else, is that the check engine light will not come on. So, in such a situation, you will have to clean the clogged fuel pump.

How To Clean A Clogged Fuel Pump

Cleaning a clogged fuel pump is relatively easy. There are a few steps you need to take, so let’s get on with a detailed explanation of each of these steps.

1. Get Ready

Before you start working on your fuel pump, there are a few things you must do beforehand. No, it is not emptying your tank as some guides suggest.

The gas itself, while liquid, is not flammable, but its vapors are. People will tell you to empty the tank to decrease the chances of an accident, but their advice makes accidents more likely. The empty tank is full of vapors.

Instead, you must assemble tools, a knife, a hammer, a few flat screwdrivers of which one must be wide and dull, a piece of cardboard, and a flame extinguisher, just for any case.

Once you have them all within your reach, you need to roll down the windows if you are cleaning the fuel pump on a vehicle.

Next, remove the negative terminal clamp on the battery and tuck it to the side. A fuel pump is an electric device immersed in the fuel; you don’t want it to be connected to a battery while removing it. There could happen some sparking, which can ignite gas fumes.

The easiest and safest way to disconnect the pump from the source of electricity is to disconnect the battery.

2. Locate The Pump

The exact location of the pump is different on different vehicles. On some, it is under the carpet behind or under the rear passenger seat, sometimes under the front passenger seat, and sometimes in the trunk.

The user and service manuals for your vehicle or generator will have their exact location, so you must consult them.

In case you don’t have them, the internet is your friend. You should be able to find either to download the manuals or precise instructions on how to locate the fuel pump.

One thing you must be very careful about. If the instruction says that the pump is located on the engine, they are wrong.

The device you will find by following them is actually a fuel pressure regulator. Technically it is a pump and it does make fuel move around, but “these are not the droids you are looking for”.

The fuel pump you are looking for is very often called by people’s fuel pump/sender unit. You will find a cover that needs to be removed.

These covers are almost always plastic, and very often have very fragile tabs that hold them secure. In other cases, you should be careful to not break plastic tabs on covers.

In this case, breaking them is not an issue. I will explain to you how to replace the cover if they are broken.

3. Remove The Pump

Now that you have located the fuel pump you can remove its cover. It has plastic tabs that very easily break. If you ever have had your fuel pump replaced, chances are that the cover is glued with silicone glue because its tabs got broken.

So, you need to cut it with a knife. Once the cover is out of the way, you still can’t remove the pump.

You first need to clean the area under the cover. You will see, it will be screaming “this needs to be cleaned”. If you don’t clean it, all that dirt will fall into your gas tank.

Once you have cleaned it, mark on the outside of the retention where a small arrow on the ring is. Then disconnect the pump’s wires and fuel line

If you don’t have a special tool for removing the fuel pump retention ring, grab the dullest flat screwdriver you have and a hammer. Now, if you look at the retention ring, you will notice tabs protruding upward right around the pump.

Put the tip of the screwdriver above it and start gently tapping the other end of the screwdriver. Work it slowly counterclockwise.

With the retention ring removed, you can’t just junk the pump out. Pull it slowly and look around it to where the float arm is, be careful to not bend it. With the pump almost out, lean it sideways so that the gas inside of it leaks back into the tank.

Now, cover the opening with a piece of cardboard, and gas fumes will exit through rolled-down windows.

4. Replace or Clean The Coarse Mesh Filter

On practically all fuel pumps the housing is made of two parts, the lower which houses the coarse mesh filter, and the upper which houses the actual pump and other electric parts.

You will need a narrow screwdriver to release the tabs that hold these two together. They are wide and sturdy but have to be pried away.

Once you open the pump housing, you will see a small mash bag-like-looking thing, which is very dirty with debris on it.

That’s a coarse mash filter, clogged and causing you all the problems you have noticed. They can be washed with warm water but depending on the vehicle they cost $5-$10 on Amazon, or around $15 a pack of 3 filter screens.

To remove it you usually have to just jank it off or unscrew it. And once you put the new or cleaned and properly dried old screen, you just need to push the lower housing into place until the tabs click.

5. Replace The Pump

Replacing the pump goes backward or removing it. But now you still have to be careful to not bend the floater.

You can either let it swing down and first insert the floater and then angle the pump into the opening, or you can hold the floater pressed by a finger to the pump housing and lean the pump to the other side while lowering it into the tank.

Retention ring you can first start screwing by hand and then slowly hammering on its tabs clockwise until the small arrow is aligned with the mark you drew on the tank, and it can’t be turned beyond it anymore. Of course, you need to reconnect the pump wires and the fuel line.

If you have broken the tabs on the cover of this compartment, don’t waste time trying to find a replacement cover. It can be sealed with silicone caulk, just by using the caulking gun draw a bead wide enough to cover the gap of the cover.

If the cover is under the carpet, wait a couple of hours for the silicone to dry before replacing the carpet.

Tips To Keep Fuel System In Good Condition

If you wish to prevent your fuel pump from clogging again, or to at least push back the date when it will happen, there are a few pieces of advice you should follow.

The first is to use only high-quality fuel. One which doesn’t have high sulfur content that leads to corrosion of tank and fuel lines.

Change the fuel filter more often than recommended, because a partially clogged filter will lead to the fuel pump straining and shortening its life span.

Also, avoid your fuel level to drop under ⅓ of the gas tank, especially in older vehicles. If your tank is almost empty, the pump could pull the sludge and grime which accumulates on the tank’s bottom.

This debris is unavoidable for many reasons but avoiding it from getting into pump housing will prevent the mesh filter from clogging, or at least slow it down.

Conclusion

Now that you know how to clean a clogged fuel pump, you can do it yourself. You should know that the mash screen you can never fully wash, and replacing it is a better choice.

They are very cheap and it doesn’t make sense to not replace them.

References

https://www.yourmechanic.com/article/how-can-i-keep-my-fuel-system-clean

Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

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