Super money saving tip!

Extended run time fuel tank for Honda 2000 generators

(and others)

Here’s en excerpt from my RV Tech Tip book of one of my many tech tips…..While dry camping I got tired of fueling the Honda 2000 once or more times a day depending on use. I decided enough of that and after a little surfing on the web decided to make my own extended run time fuel tank. I found these on line for $100 or more + shipping. The exact same thing and cost me a whopping $36!

All that is needed is….

A 6 gallon marine fuel tank. Mine is an Atwood marine tank from
Wal-Mart ($15!)

A Honda mower gas cap. Make sure the one you get fits the generator you’re using! They make different sizes with different type threads! You may also use the stock generator cap. (see below).

6′ or so of fuel line
A 1/4″ bulkhead fitting of some kind (or suitable item), usually found at marine shops.
All for under $40 or less!

The fuel line simply is ran from the marine fuel tank which has a 1/4″ pickup tube in it and then connect the other end of the fuel line to the 1/4″ nipple on the gas cap. Everyone asks what about venting since the original 2000 gas cap comes with a ventable cap. Well the 6 gallon Atwood marine fuel tank (which can be bought at Wal-Mart for $15) is vented so it accomplishes the same thing as the original cap with the ventilation knob. The fuel line and stock Honda mower gas cap was bought at a local Honda and mower shop. Talk about extended run time! You first fill the Honda 2000 tank then attach the fuel line from your 6 gallon marine tank. After about 3-5 minutes or less of run time the generator starts pulling fuel from the 6 gal tank. So basically you went from 1 gallon of fuel capacity to 7 gallons! Depending in the load on the generator you could run for several days without the hassle of having to ad fuel ever day or more often! It’s really nice not to have to go out every morning or evening and have to hassle with fueling the generator, especially in bad/cold weather.

** Additional info….. I have had many say they cannot find the 1/4″ nipple for placing in the genny cap or the right stock mower cap to fit a specific generator and/or the ¼” t-fitting. A great substitute as my son can say and works well is a simple valve stem for a set of air bags. This can be bought at most automotive stores. Look closely of the picture below. On the table you will see the valve stem. You simply drill the hole just big enough to accept the stem and with rubber washers or O-rings on each side of the cap-the nuts tighten down holding it in place and sealing the fitting. Out the bottom side (of the cap) we placed a short piece of plastic air line about 2″ long (compression type) for the fuel to run out of. Works perfectly! You slide the fuel line over the threaded valve stem, tighten the hose clamp and you’re ready to ride! When not in use you simply screw on a valve stem cap and all is well. If you decided to run the genny without the extended tank simply loosen the valve stem on the cap and away you! No need for 2 different caps!

Here are some pics of my setup……

The 6 gallon marine tank itself with the Honda mower cap (replaces the stock gen cap) (Keep your stock cap!)…..with 1/4″ bulkhead and fuel line…..


The setup running…..Please note the tank is only sitting on the picnic table for photo op. It works at, below or above ground level. It creates its own vacuum.


Such a sweet deal for just over $30, but like I said earlier if you’re the adventurous type you can always order this setup for $100 plus shipping lol! What just kills me is these things sell on line for over $100! I and others have seen this almost exact thing for sale on line and in booths at RV events for nearly $100. Keep track of all your mods and expenses as well as everything else in your RV world with the best RV management software there is, RV Notebook! The best of the best, very interactive and fun to use!


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Leave a Reply


  1. I have a water cooled Honda EU6500 generator. All extended run fuel systems seem to be for smaller (suit case type) generators. Is there any reasion that your idea would not work on the EU6500 Honda.


  2. Les,
    The same thing happened to me as well and it was due to a very small vacuum leak in that I thought it was airtight and was not. Try a couple small hose clamps where the fuel line is attached to anything to be sure. I have 2 setups running fine on this. I don’t have a “T” as I only run one so I’d imagine your “leak” is at the “T” maybe. sure sounds like a vacuum leak to me.


  3. Les

    I have tried the set-ups you have ,but I’m not getting the fuel to flow to generators. Everything seems to be air tight. The only vent is on the marine tank that is open.
    I’m using 3/8 rubber hose. I drilled out the stock caps and inserted brassbulkhead fitting . I’m using a brass tee also ,so I can use both Hondas at the same time. I did try hooking up to just one Honda and still no luck
    does anyone have any suggestion why this is not working?

  4. Apparently I do no have a closeup pic. The cap assembly part is not hard to do. In fact I have found the mower cap increasingly harder to find so one can use the stock cap as my son did with the airbag valve stem setup or the 1/4″ bulkhead fitting and it works fine. Simply as stated take apart and out the stock fuel cap vent assembly and drill if you need too to accept the bulk head fitting or airbag valve stem and put in place. If using the airbag valve stem use a small hose clamp when attaching the fuel line to assure an airtight fit. when using the airbag valve stem simply put a valve stem cap on for storage. As well if you (as stated above) want to use the generator without the extended tank simply loosen the valve stem cap asnd it works fine which actually makes it better than the 1/4″ bulkhead fitting. The whole cap process took only maybe 10-125 minutes to do. Pretty easy. The entire project was maybe a half hour or so.


  5. Dave I’ll check and see if I have a closeup pic to provide as my son currently has my generator at the moment camping.

  6. Dave Beach

    could you perhaps provide a very closeup photo(S) of what you did with the 1/4″ entery into the Honda fuel cap???

  7. Darthvagrant

    I have an EU1000 generator in addition to my 4KW (noisy) Onan. My EU1000 lives behind the grille and is fed directly from my rear fuel tank. My rear tank is 40 gallons, in addition to my front 38 gallon tank. The Honda runs with the control on the Honda in the ‘off’ position. I tapped into the Honda tank-to-carb hose and provided an (electrical) remote on / kill switch both under the hood and inside the coach, with an LED at each to indicate when the Honda (fuel pump) is ‘on’. The Honda is fed by a low pressure electric fuel pump on the rt. frame rail (from the rear tank) with the pressure further reduced with a pressure regulator @ .around .080 millibar (very low, since the carb is designed for gravity flow)
    The gas hook-up is a fitting provided on the case of the Honda. This has virtually replaced my coach battery for extended dry camping. I also discarded the onboard 110 / 12V power supply in favor of an adjustable Pyramid 110 / 12 V supply that is much cleaner. I have a digital volt and ammeter on ther dash to monitor the battery voltage at a stable 13.8V, keeping track of what’s going and coming from the battery, and adjust as necessary. Running the Honda consumes about 4 gallons a day MAXIMUM so I can “stay put” for a really extended time now. I only run the Onan for air conditioning or the microwave. There’s a little more to this project, but those are the major points.
    As a side caution: The Hondas do NOT have either side of the 110 going to ground. Each side is 55+/- to ground, with the full voltage between the conductors. The Honda oputput CANNOT be combined with the coach ‘factory’ 110 system. It becomes necessary to separate the two circuits. If not, you’ll put 55VAC into the 12V DC circuit of your referigerator. The magic smoke will escape from the reefer electronics. D’oh! Found this out the hard way, having to repair the electronics in my Norcold refer.

  8. Ken Priest

    I have a Class A motor home which originally had a gas engine. Some idiot converted it to desiel. Problem: generator uses gas. I used a simular solution to yours. I use a 12 gal. marine tank. I tapped the cap and installed a quick release air hose connector. Air line runs out through the body for venting. Works great!