FAQ'S about Mr. Funnel Flo Tool Fuel Filter

FAQ'S about Mr. Funnel Flo Tool Fuel Filter


  • Fuel and its vapours are extremely flammable and explosive. Fill fuel tank outdoors, away from open flames, sparks, heat, and other ignition sources.
  • Static electricity can ignite fuel and its vapours. Properly ground funnel, according to owners manual of the equipment you are refuelling. (Only black models are conductive and can be grounded)
  • Do not overfill tank. If fuel spills, wait until it evaporates before starting the engine.
  • Some droplets of fuel may remain in funnel after use. Do not store funnel in a plastic bag or another sealable container because that will prevent fuel from evaporating. Store funnel with same safety precautions as you would store any fuel.


  • The funnel is designed for use with most gasoline, diesel, heating oil, and kerosene fuels. Ideal for use with lawn equipment, agricultural equipment, watercraft, ATV, etc.
  • Test funnel before each use. Add water to funnel to cover bottom 1/3 of the filter. Water should not pass through.
  • Fuel additives and stabilizers may allow water to pass through the filter. Add additives directly to the tank.
  • If fuel has been shaken (for example, in transport) let it rest several minutes before filtering; otherwise, water in fuel could pass through the filter.
  • Do not attempt to remove the filter from the funnel. It is permanent.
  • Do not wipe out or clean funnel after use.


  1. Insert funnel into the item to be filled. Keep funnel level.
  2. Pour fuel into funnel but not directly onto the filter.
  3. “Dump the sump.” Water and debris will collect in the sump, the area below the filter. Pour sump contents into a separate approved container and treat as hazardous waste. Note: As water collects in the bottom of the funnel or if flow rate slows, stop refuelling and “dump the sump.” Funnel requires no cleaning.



Q. When do I need a conductive model?

A. To comply with aviation and marine regulations, your refuelling system needs to be grounded. Only conductive funnels should be used. The probability of a static fire is greater with gasoline but certainly possible with diesel. Also, the more fuel you pump, the more static is created by the fuel flowing across the surfaces getting into your tank. All Mr. Funnel models that are BLACK in body colour are conductive. 

Q. What makes the funnel conductive?

A. Carbon is injected into the raw materials and makes it just conductive enough to bleed off static electricity as it is generated by the refuelling process when it is properly bonded or grounded. 

Q. How do I clean the funnel?

A. You don't. Since the screen is coated with Teflon, nothing sticks to the screen. Just turn it upside down and tap it on the rim. If some particles remain just ignore them because they won't go through. No chemicals, no brushes, just leave it alone. 

Q. Can I buy a new replacement filter?

A. No. We once sold them but realized we were doing our customers a disservice. They don't wear out so if you bought one it would be lost long before you needed it. Also, if we did sell them, they represent the majority of the price of the whole unit so you might as well buy a new funnel.

Q. How will I know if I have contamination or not?

A. Just tilt the funnel to one side and you will be able to see water and dirt under the remaining fuel. If you are experiencing a large amount of water, stop frequently and empty out the water and resume refuelling. It's that simple.


Q. What do I do with the stuff left in the sump at the bottom of the funnel after refuelling?

A. This technology requires the sump to help separate the contamination from the fuel so it can't be eliminated. You can pour it back into the gas can you were using or have a separate container to place it into. When the container gets full you can run it back through the funnel and you will never waste a drop of useable fuel.


Q. Can I get replacement parts?

A. No. The funnels are self-cleaning and no replacement parts are needed.


Q. How do I test it?

A. First of all, test the funnel with one cup of water in the medium funnel and two cups of water in the large funnel. If no water passes the screen, the screen is working properly. Although the screen can sometimes catch more water than this, it is not designed to. Water is almost 25% heavier than some fuel and this extra weight builds head pressure which can force the water through the screen. Empty the water as it collects to avoid problems.


Q. How often do I need to test the funnel?

A. If the funnel has not been in use for 30 days you should test it with a cup or two of water to be sure it was not damaged since your last use.


Q. Will the filter work on mixed fuel with 2-cycle oil in it?

A. Yes, but if your 2-cycle oil has a detergent base the detergents can break down molecules of water and some water might pass the screen. Usually only a drop or two but if you are concerned, filter the fuel a second time because unless the sump is full of water, it is not possible that any water passed the filter.


Q. What happens when I use alcohol or fuel additives?

A. Most additives absorb water so add them to your fuel tank and not to your fuel cans or they will bring water into the tank with them.


Q. Can I use the funnel on all fuels and do I need to clean it before I switch?

A. You can use the funnel on all fuels and since the surface doesn't absorb any fuel there is no need for cleaning.


Q. How long will the filter last?

A. Sorry, but we have no idea. Some units are over 10 years old and still being used on a weekly basis and work as well as the first day they were put into service.

 Q. What makes this funnel different from other funnels with screens in them?

A. First of all the filter is vertical and receives has no pressure on it in relation to a funnel with a horizontal screen. Horizontal screens are quick to clog and difficult to clean. Second, a Mr. Funnel Fuel Filter is Teflon coated and nothing sticks to Teflon, and the screen opening is small enough to repel the water.

Q. Which model do I need?

A. If you are transferring more than 5 gallons at a time the larger F8 model is recommended because it is easier to use and you will be less likely to spill any fuel. If you are transferring 1-5 gallons the F3 will be adequate, and for small uses like lawn mowers and small generators, the small F1 is recommended. Its flow rate is fast and this model is small and can remain with the equipment you are refuelling.

Q. Won't using the funnel slow me down at the pump?

A. Yes. But you can use the funnel as a testing device if you are going to transfer a large quantity of fuel. If you are going to pump 150 gallons test the first 5 or 10 gallons and inspect the bottom of the funnel. If no water or contamination is visible in the funnel, pump directly into the tank and make another check at 50 gallons and 100 gallons. Usually, if there is no contamination, to begin with it means that the vendor is taking good care of his filters and you won't need the funnel. If, however, you find any contamination you are better to slow down and use the funnel for the whole refuelling process or go to another source.

Q. How do I use this for automotive or motorhome use?

A. The downspout of the F-15 is the same size as 1" PVC pipe which can be added to reach any fuel tank. In line on/off valves can also be installed for more control. (If PVC pipe is used, a bonding wire should be attached from the funnel to the filler neck of the fuel tank to control static problems.) 

Q. What are the two tabs at the bottom of the large funnel for?

A. To stop the swirling of the fuel so it can go down the spout faster.

Q. Do I need a top for the funnel to protect it and keep it clean?

A. No. The screen is tough and difficult to damage and if some dirt happens to get into the funnel body don't worry, it won't go through.

Q. Do the funnels work at different temperatures?

A. The National Guard in Alaska has used them at 40 degrees below 0 with no problems at all. They are also very popular in Australia, Brazil, and Africa with much, much warmer temperatures.

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