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Changing a Fuel Filter on a Class A Motorhome

Fuel is the lifeblood of your engine. Ensuring that lifeblood is clean and contaminate free is very important. The fuel filter on your motorhome will pull out the gunk that may be in the fuel and keep it out of the rest of the fuel system. Over time this gunk will build up and either clog up the fuel filter, or just begin to bypass it since there’s no more room to catch it. Some of these contaminants are just going to reduce your gas mileage, while others can cause serious and permanent damage to your engine. Changing a fuel filter on a class A when it’s dirty will get you better gas mileage and keep your rig running the way it should for longer!

How the Filter Works

As the fuel is drawn from the fuel tank and pulled through the lines, it goes through the fuel filter. This filter is made up of a special paper that will collect any dirt or large particles. If these particles get into your engine, the force and speed of the pistons can actually push them around and cause serious damage. Unfortunately unlike some filters you may find on your rig, fuel filters cannot just be cleaned out. They need to be replaced regularly as they fill up with dirt and rust particles.

When and How To Change It

Before we talk about changing the filter, you should know about another important task that you should be doing every time you fill up your fuel tanks. On the filter is a drain valve. One of the jobs of the filter is to separate water from the fuel. Since the water is denser than the fuel it will collect in the bottom of the filter. You want to drain off the water every time you fill up! Keep a clear jar on hand for this purpose. Holding the jar under the valve, twist it to release the water. Allow it to drain until you start to see the fuel come out. If you’re lucky, you’ll have the green kind that will be easy to spot. Now that you know you should be draining the water, let’s get into changing that filter!

You want to change your filter as part of your routine yearly maintenance at least. If you are putting a lot of miles on your rig each year, you may need to change it more often. Some of the signs of a dirty fuel filter are:

  • The engine stalls, especially when on an incline

  • The engine won’t start

  • It takes more time to start

  • Hesitation when accelerating or climbing an incline

  • Better performance at high speeds than low

Please note that changing the fuel filter on a class A will vary from motorhome to motorhome. The premise is the same, but always be sure to look for specific instructions on how to change your particular filter.

The contents of the fuel system are usually under pressure that has been created by the fuel pump. You want to release this pressure before you remove the filter so that it doesn’t come blasting out at you. Most of the time you can do this by simply removing the gas cap. However some may require that you remove the fuse to the fuel pump, and then idle the engine until it dies.

First you need to find where your filter is! The filter is usually in either an access panel near the engine which is very convenient, or right up in with the engine itself. Look it over and gather any tools you may need before hand. Sometimes you will need a set of hex or allen wrenches. You will also want to have a lot of rags to collect any spilled fuel.

You will find three pipes/hoses on the top. Be sure to note which one is which so that you don’t hook them up to the new filter backward. They are made to only go one way. We find that if the lines are not already marked, placing a piece of tape on one will help you know which one is which. The center hose is usually a different type of connector so you usually only have to pick one to define to know where the rest go back in. Place some rags around the hoses before you remove them to catch any fuel that spills out. The hoses should be held on by clamps that can be loosened with a screwdriver until they can be wiggled off. In the center you will most likely have a clip that needs to be triggered to get it off. It will then pull up and out. There will be a wire that is connected to the water sensor. Some are on the top, and some are on the bottom, but these will just unplug. Remove the water valve mentioned earlier and drain all the contents out of the filter in to a container. This will be a fuel and water mixture.

Now that you have the connections off, you need to find where the filter is anchored to the RV. This can sometimes be a pain to get to, and some will require you use either a hex or allen wrench. Once you have this/these screw(s) off you can pull the filter out. On the bottom of the filter when you pull it out you will find the water sensor. This needs to be turned and pulled out because you will need to put it into the new filter.

Wipe the water sensor clean and put a little grease on the threads before installing it into the new filter. Now just press it into the filter and twist! Place the new filter down into position & put the screw back in that holds it in place. Now remove the plastic caps that protect the pipe fittings and then grease those areas as well. Replace the water valve you took off screwing it in only hand tight, and then plug in the electrical connector. Using a funnel, fill the filter up with clean fuel! Don’t use the stuff that came out of the old one; it’s counterproductive. Now that you have it filled, you can refit the 3 hoses that came off the top. This is where you need to be sure you are connecting them in the right order! The filter should say which is in and which is out and you should have at least one of the hoses marked so you know what’s what. Press the clip back into position when you put the center hose on. Check to make sure that there are no leaks coming from the filter. Then start the engine, and check it again. Let the engine idle for about 10 min to get out any air bubbles that may be in the system from the change.

That’s it! You’ve done it! Pat yourself on the back and have a beer, because you deserve it you handy RVer you! Changing a fuel filter in a class A motorhome is usually pretty simple. If you feel that yours is beyond what you can or want to do, keep in mind that you can always take it to a diesel engine service center and have it done for you. Don’t just avoid it. The damage it can cause can be serious and may require major engine work if it can even be repaired. This is a small job to take on to ensure that damage doesn’t happen.

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