The clogged fuel filter is a common yet sometimes overlooked problem when dirt bikes fail to start, hesitate once running, frequently stall or just straight up give erratic performance.
Once clogged, fuel obviously can't get to the engine. It would be similar to pinching the fuel line. Using high quality race fuel usually eliminates the need for a fuel filter as most carbureted dirt bikes don't stock a fuel filter (though some riders install one later for extra protection) but also prevents clogged filters on those with them and delays the time between changes.
Unlike carbureted dirt bikes, most fuel injection bikes have a fuel filter and therefore pose the most problems once clogged. The same applies to ATVs though some Utility ATVs feature an OEM fuel filter on carbureted and fuel injection systems. The mouth on an injector is much smaller than the jet on a carbureted bike thus the reason for the required fuel filter on a fuel injection.
Saying it's easy to change would be a big fat lie. Make no mistake - it's a pain. Plus you've got gas everywhere and the fumes so hold your breath.
The fuel filter is located in the fuel tank on the end of the fuel pump. Once it clogs it requires changing and to remove it, the fuel must be drained and the fuel tank removed. Unless you're quite adept, we'd highly suggest a mechanic to do the dirty work.
A carbureted bike with a fuel filter is a bit easier therefore read How to Replace the Fuel Line In a Dirt Bike for instruction on removing the fuel filter. You follow the same steps to replacing the fuel line since the fuel filter is attached to the fuel line.
A number of issues mimic a clogged or dirty fuel filter including:
- Bad spark plug
- The stator
- Stuck float
- Clogged jet
Read Help! My Don't Bike Won't Start for more issues that affect bike performance. If it's been a few rides since the fuel filter replacement it might be worth your time to start there since it's often overlooked.
This photo shows a brand new fuel filter (the white piece in the middle) next to a 12 month old fuel filter (the black piece) used on premium pump gasoline
When to change the fuel filter depends on the quality of gas used and the amount of time riding the bike. Some riders opt to schedule the fuel filter change for example, every time the oil and air filter gets changed. Your best bet is to check the manufacturer's service interval hours or if you're like a lot of riders forget about it and wait until it poses a problem. But don't get mad if it ruins race day or you're stuck at a campsite while your friends rip through the trails!
It's also not a bad idea to install a Twin Air Fuel Filter if your bike doesn't have a traditional fuel filter or in addition to an existing filter. It fits securely under the gas cap and is a cinch to install and remove. It's not as effective as an internal fuel filter but provides an additional layer of protection if you frequently experience a clogged filter or clogged jets if your bike doesn't have a regular fuel filter attached to the gas line.