Many motorcycle riders rarely change the fuel filters. If ever.
Heck. Most even forget that there is a fuel filter in their motorcycles.
You should be changing the fuel filters regularly though. At least once every 100,000 miles.
In case you haven’t, change it when it goes bad and gets clogged up.
So, here are the symptoms of a bad filter in a motorcycle:
- Motorcycle cranks but doesn’t start easily
- Engine malfunction light ON
- Fuel pump whines
- Engine runs lean
- Motorcycle stalls a lot
- Fuel efficiency decreases
- Pungent fuel smell
The first 3 symptoms are clear giveaways that something is wrong with the fuel filter.
So, let’s discuss these symptoms in detail.
Symptoms of a clogged fuel filter
Let’s dive right into the major symptoms of a clogged fuel filter in a motorcycle.
#1. Motorcycle cranks but doesn’t start easily
Whenever the fuel filter is clogged or not working right, the fuel flow to the engine gets disrupted.
So, if your motorcycle cranks but not starting:
Then, enough fuel is not going to the engine.
Since the fuel filter is clogged, the engine won’t receive sufficient fuel for combustion.
Of course, there might be other causes as well for the motorcycle to crank but not start.
But insufficient fuel flow into the engine is the main cause.
Sure, even within fuel flow, there might be other problems: low gas level, fuel pipe broken, and carburetor issues. But a bad fuel filter is one among them.
Combined with the other symptoms mentioned below, you should be able to narrow it down to the fuel filter.
#2. Engine malfunction light ON
Whenever the fuel filter has gone bad, the engine does not receive the fuel properly.
And whenever the engine is not working right, the engine malfunction light turns on.
You can clearly see the indicator on your motorcycle display.
Of course, having the engine malfunction indicator switched on does not necessarily mean the fuel filter has gone bad.
Any engine problems will be reflected on the indicator.
But its a good giveaway that can be used to check the fuel filter condition.
#3. Fuel pump whines
For fuel-injected motorcycles, fuel pumps are essential.
If the fuel filter is not in good condition in these motorcycles, the fuel pump will face troubles in smooth functioning.
This is often accompanied by the fuel pump making a whirring noise.
So if the fuel pump is whining and making noise, that’s another symptom of the fuel filter getting clogged up.
By now, coupled with starting problems and the engine malfunction indicator – the fuel pump noise should make you look into the fuel filter closely.
#4. Engine runs lean
Whenever the fuel filter is clogged, not enough fuel gets through the filter and finally reaches the engine.
As a result:
The engine doesn’t get sufficient fuel for combustion.
The fuel mixture will be – too much air, and too less fuel.
Leading to the engine running on a lean air-fuel mixture.
This is one of the major problems whenever the fuel filter is clogged.
The lean mixture in the engine gives rise to several other problems including low power, low fuel mileage, and engine overheating.
#5. Motorcycle stalls a lot
Stalling is when your motorcycle comes to a sudden halt because of insufficient power transmission from the engine to the rear wheel.
A clogged fuel filter does not allow the fuel flow to the engine to go smooth.
What ends up happening is:
The fuel flow is disrupted. The engine receives the fuel irregularly.
And when the fuel in the engine gets low, the engine won’t generate enough power.
When the engine does not generate sufficient power (especially at higher gears) – the motorcycle starts stalling.
That’s another symptom of the fuel filter not working good.
#6. Fuel efficiency decreases
Poor gas mileage is another symptom.
Inefficient fuel combustion always leads to decreased fuel efficiency as well as fuel economy.
The fuel filter clogging up makes the engine receive irregular fuel amounts.
As a result, the motorcycle engine won’t utilize the fuel well.
Lots of fuel exits the engine without burning completely to generate maximum power.
Thus leading to low fuel efficiency and poor gas mileage.
#7. Pungent fuel smell
Although this is not universal, another symptom of a clogged-up fuel filter is the pungent fuel smell.
The fuel smell gets much more noticeable near the gas tank and the engine area.
It can also be coming from the exhaust. But the motorcycle gas tank and the engine are the prime areas.
If you are smelling the fuel, make sure you check the fuel filter as well as the fuel pipes.
How to confirm
Now that you have noticed the different symptoms indicating problems in the fuel filter, you must check it to confirm.
The fuel filter is usually located right below the gas tank. Attached to the gas tank itself.
For fuel-injected motorcycles, the fuel filter is located along the fuel lines.
Start from below the gas tank, and check how the fuel flows. You should be able to find the fuel filter near the fuel pump.
In some cases, the fuel filter might be inside the gas tank as well.
Once you have found the fuel filter, dismantle it. Take it out.
Some filters have their paper pleats open. And some are enclosed with a cover.
If enclosed, take out the casing to see the paper pleats clearly.
Before that, you can simply empty out the fuel in the filter and check how dirty the fuel is.
That fuel from the filter itself is an indicator of the fuel filter condition.
Observe the pleats.
Are they blackened? Is there sludge formation? Does it have too much dirt and deposits?
If yes, then the fuel filter is clogged up.
It is not in a good working condition.
Solution – Cleaning/replacing the fuel filter
Since the fuel filter is clogged up, the next steps are pretty straightforward.
If the filter is NOT blackened, but has some deposits formed, you can clean it up easily.
But if there is too much dirt and the pleats are blackened, then it’s better to replace the fuel filter with a new one.
You must replace the fuel filter once every 100,000 miles (160,000 kilometers).
Here’s how to replace the fuel filter on your motorcycle:
Few filters have a button on them. You press it, you can remove it out.
Few filters can easily be taken out by hand by applying some fore.
But most fuel filters, you need some more effort.
Take the wrench.
Turn the reserve fuel switch OFF first.
Next, loosen the nuts on each side of the fuel filter.
Take out the old fuel filter. You might have to apply force and pull out the fuel pipe from the filter.
Next, fit the new filter in the same place.
Connect the fuel pipes. Tighten the nuts – first with the hand and then with the wrench.
You have now replaced the fuel filter.
The main symptoms of a bad fuel filter on a motorcycle are – the motorcycle turning over but not starting; engine malfunction light ON; and whirring noise from the fuel pump.
These symptoms are more than enough for you to check the fuel filter.
If the fuel filter is indeed clogged up, replace it with a new one.
By thumb rule, you must replace the fuel filter on your motorcycle for every 100,000 miles traveled.
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