ATV Fuel Filter Not Filling Up: Troubleshooting

If you’re reading this post, your ATV is probably sluggish and bogging down. You may have checked your fuel filter and discovered your filter is only half full. This post will help you determine why your ATV fuel filter is not filling up.

empty atv fuel filter

Too Little Fuel

If you don’t have enough fuel in your ATV, it may not have enough flow to sufficiently fill the fuel filter. This is particularly likely to occur on inclines and with gravity feed fuel systems.

To keep your ATV fuel filter not filling with gas from causing your ATV to hesitate or even stall, plan your trip so you don’t run low on fuel or ride on even ground in the second half of your riding trip.

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The petcock controls the flow of fuel. If a valve inside it inhibits the flow of gas, it won’t fill your fuel filter to send gas through the rest of your ATV.

To check this, disconnect the fuel line between your gas tank and your petcock to see how that impacts the stream.

Obstruction in The Fuel Filter

The fuel filter itself may be to blame when your ATV gas filter isn’t filling. If there is an obstruction inside the filter, fuel won’t be able to flow through it.

This will probably occur in old or dirty filters. If yours fits either of those categories, go ahead and change it. Even if nothing appears to be wrong with your filter, you could substitute a new filter to see if it fixes the problem.

You may have a second fuel filter inside your carburetor. Check your owner’s manual to determine if you have one and make sure it isn’t obstructed. It could be preventing fuel flow to your main filter.

Filter Positioning or Size

Your filter may simply not be installed in the right direction. Inline fuel filters are usually meant to be installed facing a certain direction. There will be an arrow on the filter pointing to the carburetor. If you have this type of fuel filter, make sure it is facing the right way.

Fuel filters are also meant to handle a certain amount of fuel. If you have too large a fuel filter in your ATV, it will fill much slower than the fuel filter you need.

Old Fuel Lines

As fuel lines age, they become porous. When they do, the fuel pump can take in air.

If your fuel lines may be old, check them for cracks. Also look at the line clamps for signs of old age or damage.

Gas Tank Obstruction

If some foreign object got in your gas tank, even a small one, it could clog the drain in the gas tank that lets gas enter your fuel system.

If nothing is wrong with the other components of your fuel system, you might need to remove and check your gas tank.

Restrictive Gas Cap

Gas caps are made with vents to let air into the gas tank, because without the air going in, the gas can’t go out.

Take off the gas cap, start the engine, and then check the filter.

Bad Fuel Pump

Fuel pumps make it possible for the gas to leave the gas tank and move on through the fuel system. When something goes wrong with them, this causes there to be no fuel in ATV fuel filters. There are two different kinds of fuel pumps: electric and vacuum.

To make sure your electric gas pump runs, you can:

  • Turn on the ignition, crank, and listen to the pump. Someone else may have to help you do this.

  • Examine your power supply, fuse, and relay

  • Look at your ground connection

  • Run power to your fuel pump and ground to hot wire it for a test

  • Blow air through it.

With a vacuum pump, first find the pump and examine the fuel lines that run to and from it for defects and kinks. Look at the fuel pump’s supply pipe. Then remove the fuel line that leads to the vacuum pump and crank the engine while someone feels at the carb to see if they can feel suction coming from it. There should be a significant amount.

With either type of fuel pump, it may be able to run but still lead to an ATV fuel filter not filling up. Once you determine it can run, you still need to check its pressure with a pressure test kit.

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