Recently I wrote about our Honda “EU” series generators for use in extremely hot weather to run our camper’s air conditioner. One thing I didn’t discuss in much detail was the limited fuel capacity their built-in gas tanks have. At the time I mentioned I would be purchasing an after-market extended run fuel tank. The generators barely had enough fuel capacity to run through the night, and had it been hotter or more humid they would have run out of fuel.

Disclaimer: Usually I include a disclaimer if I receive any commission from any links in a post. After researching tanks, I only found one that I was comfortable buying – that is, given my professional experience working with fuel systems, the one I bought was the only one I felt was safe. I paid the regular price, I don’t know the seller, and there is no financial benefit for me to review the product. I could have linked to some tanks that might generate income for me, but I am unwilling to do that.

This post will review the extended run fuel tank and accessories.

Honda does not make an extended run tank for their generators. I suspect it is because their lawyers are paranoid. However they do sell external fuel systems for their outboard motors. The extended run system I bought is made from standard marine parts, some of them sold by Honda.

Seller Background

First, we must review some facts about the components and the seller.

• The seller is on eBay, with over 5,000 feedbacks and a 100% rating.
• The seller assembles the system himself and lives in the U.S.
• The seller is a disabled veteran. This doesn’t mean one should necessarily buy from him, but if he is making the best product that might cost a little more than inferior products on the market, it is a double win for the buyer.
• I had a couple questions about his system, specifically if the gas caps would work on both our EU2200i and our EU2000i Companion Honda Generators (yes they do). I emailed him via eBay around 10pm at night. He responded almost immediately and also answered a couple other emails the same night. Who does that these days?
• He uses Moeller tanks and fittings. I use Moeller products on our outboard motor when we use our boat. They are top rated products. Moeller tanks are solid units, and they don’t become misshapen in hot weather. I read reviews of some of the other brand extended run tanks that get bloated in hot weather when the gas expands in the tank. Those reviewers think their 80F weather is hot. We often operate our Moeller tanks in 120F weather with zero problems.
• The fuel lines are made from Mercury 5/16″ EPA Approved “Premium Fuel Line” with a Genuine Marine Rated Fuel Connector from Honda. Mercury is one of the largest marine companies in the world. We own several Mercury products and have been completely satisfied with them for the past 15 years or so.
• The seller manufactures the system gas caps using a computerized CNC machine from a single solid piece of 6061 T6 aluminum.

I found many systems for sale that used cheap parts and some that were using fittings designed for air hoses not marine fuel systems!!

How the Extended Run Fuel Tank System Works

The 6 gallon external tank, fuel lines, and gas caps connect to both Honda generators. Yes, one tank provides fuel for both generators. It is a dual run system. At ¼ throttle it would probably run continuously from 80 hours.

Many marine applications use a “squeeze bulb” to prime the fuel line from a remote tank to the engine. Our boat does this. However, the Honda generators have a fuel pump, so if the generator tanks are full and the extended tank is connected, as the internal generator fuel tanks level drop the fuel will flow from the external tank to the generators. The seller does sell a dual run system with a “squeeze bulb.” Below is a picture of the system with the squeeze bulb from the seller’s eBay Store. I haven’t needed one, but have a couple at home for our boat should the need arise in the future.

The fuel tanks also have a built fuel level indicator. The fuel fittings are quick release, so no tools are needed. It takes about 30 seconds to connect everything to your generators.

Parts for the system: one gas cap for each generator (keep the originals!), one dual run hose, that connects to the fuel tank, two fuel lines (one for each generator).

There is only one thing the user has to change or “modify.” The original Honda gas caps have plastic retainers that keep the caps attached when refueling. These retainers have to be removed because the extended run caps must be used when using the extended tank. During transport, the Honda caps should be put back on.

You can see the cotter pin in the gas cap. The pin and other parts are removed to gain access to the retainer. Then everything else is put make in the cap. Make sure you note the order of parts and their orientation, in case you drop it and things get scattered – I did that on the first cap. Take a picture first. It takes all of 15 seconds to remove the retainer if one isn’t clumsy.

The pictures below show the fuel fittings, which are designed for marine fuel systems.

We won’t be taking the generators on most of our trips – we have a solar system that normally provides all the electrical power we need. I bought a plastic tote to store all the extended run tank components, and other maintenance items for the generators. The generators, extended run system, and the gas can are all stored on a single shelf in the garage. The way I won’t forget anything when we need to take our generators with us. Oh… and should we have a power outage, when have some back-up power too.

The seller also markets kits for a single generator and a lot of other generator-related stuff. Here is the link to his eBay site.

One last thing. The kit includes instructions. Read them carefully – they are not difficult to read – but fuel systems are potentially dangerous if safety procedures are not followed.

Update: December 14, 2023: I have this doohickey in the Admin section of my website that tells me if a link to another website is broken. The link to the eBay seller is no longer valid and it appears he is no longer on eBay. I have researched many similar systems, none of which I would feel safe purchasing. I would love to have a link to Amazon where I might make a small commission. However, there is not a product I feel comfortable with. I was an auto mechanic for decades and am very safety conscious when it comes to gasoline products.