Back To Basics: Renewing fuel filters

Rob Hawkins looks at one of the potentially messy and problematic service jobs on petrol and diesel engines; changing the fuel filter.

Most vehicles have some type of fuel filter, although not all of them can be renewed. Some are located inside the fuel tank and are not a serviceable item, whereas most fuel filters are renewable.

There are generally two locations for a renewable fuel filter; either inside the engine bay or underneath the vehicle. The work involved in replacing it usually starts with checking that all connections to the fuel filter (fuel lines and electrical plugs) can be detached, which is much easier to do with the fuel filter firmly mounted in a cage or clamp than when it has been released and is loose. However, it’s not always possible to access all of the fuel line connections or electrical plug connectors when the fuel filter is still mounted, so it may be a struggle after all.

After releasing the fuel filter, it needs to be swapped over. This is generally the messiest part of the job, with fuel leaking out. In some cases, the fuel will be under pressure, and there may be a means of releasing that pressure before the fuel lines are detached. In other cases, it’s a matter of catching the fuel that leaks out and trying to be as quick as possible. Having a drain bowl underneath does help to catch spilled fuel, although it doesn’t always leak out.

Once the new fuel filter has been fitted and connected, it may need to be primed

before the engine can be run. We’ve covered this over the following pages, along with the various means of renewing a fuel filter. Once the engine is running again with the new fuel filter fitted, it’s important to look around it to check for fuel leaks. And wear disposable gloves when renewing a fuel filter to avoid the risk of the fuel damaging your skin.