Recently I was asked to post my external fuel tank mod by another forum member, so here we go!

Following is the list of items I used to add an external fuel tank for the Honda EU2000 generator. Cost of this project will run approximately $80 dollars including the external fuel tank.

Important: Please read instructions completely before starting project!

Parts List:
Extra Generator Fuel Cap - Wise Sales or Honda Generator Distributor
3/8” O.D. Polyethylene Tubing 1ft. - Hardware Store
5/16” Rubber Fuel Hose 2ft. to 3ft. - Hardware Store
J.B. Weld - Hardware Store
Washer’s for Tank Elbow (if needed) - Hardware Store
Hose clamps for fuel hose - Hardware Store

Following items were purchased from Boating Store model numbers are Boating Store numbers. Enter numbers in Advanced Search!

1 Marine above Deck Fuel Tank 3 gallons 2-620003 $27.99
1 Tank Elbow ¼” NPT 2-200160 $5.29
1 Force Male Quick Connector ¼” NPT 2-220060 $7.39
1 Force Female Quick Connector 5/16” 2-220080 $12.99
1 Fuel Hose Barb Male Thread ¼” NPT 2-200010 $3.39

Modify the Fuel Cap

With the fuel cap installed on to the generator with a tight fit. Mark the cap at a point where you will want the quick connector to point when the project is finished. Remove the fuel cap and remove the slip pin from the bottom of fuel cap and remove parts. Remove O-ring that is under the vent switch and the gasket inside the cap taking care not to damage them. Gas cap and gasket are the only parts that will be needed. Save other parts for possible future use or repair.

Drill the existing vent hole for the tank elbow – 2-200160. The hole, when finished should be smaller then the male end of the elbow allowing it to be threaded in with a tight fit. (Threads on the elbow are tapered) I believe I used a 3/8 drill. Check alignment, install washers if needed.

Install Pickup Tube

Remove the elbow from the fuel cap and take the polyethylene tubing and tank elbow. “Do not cut tubing at this time”. Heat one end of the tubing, do not melt or burn. Press fit the tube into the male end of the tank elbow. Trimming of the tube end may be required to press the tube into the elbow. When finished the tubing should have a very tight fit. Cut excess tubing, square, not at an angle. Leave enough tubing on the fuel cap, so that the open end is positioned at the bottom of the neck on the generator fuel tank, about 3 inch’s.

Fuel Cap Quick Connector

Install the male quick connector 2-220060 onto the tank elbow 2-200160 with Teflon tape.

Thread the tank elbow with pickup tube, washer if needed and quick connect fitting just installed and thread into the vent hole of the fuel cap. Position the fitting to the mark made earlier. Place fuel cap onto generator with a tight fit and check orientation of the connector. If quick connector is orientated to desired position, proceed to next step. If not remove or add washers to correct the alignment.

Applying J.B. Weld to Fuel Cap

Caution! Once J.B. Weld has been applied and dried to the fuel cap, it will be almost impossible to remove. Make sure fittings are in the correct position and straight before applying J.B. Weld.

Take J.B. Weld (read instructions that come with J.B. Weld for proper mixing and curing time) and mix enough to seal around the tank elbow threads protruding inside the fuel cap. (Do not place any on the polyethylene tube). You will want to apply enough to seal around the tank elbow threads but not more then what is needed. Don’t go crazy. J.B. Weld will settle and pool around the threads. Set fuel cap aside on level surface to dry over night. Once dry, reinstall the gasket that fits inside the fuel cap.

Fuel Hose

Install hose barb 2-200010 with Teflon tape and install into external tank pickup connection. Slide both hose clamps on to fuel hose, slide hose onto the fuel barb and tighten the first hose clamp. Take quick connector 2-220080 and install onto other end of fuel hose and tighten second hose clamp.


Fill the generator and external fuel tanks. Install the modified fuel cap and then connect the fuel hose. Make sure the vent is open on the external fuel tank and start the generator. Check for leaks and let the generator run to verify that a vacuum is being created and drawing fuel from the external tank. If working properly the fuel level in the generator fuel tank should never be below the bottom of the pickup tube on the fuel cap when installed.

Option: You can use two quick connectors, one on each end of the fuel hose. This makes it easier to disconnect the external tank and take to the gas station for filling. This will require two sets of the quick connectors one set in place of the hose barb 2-200010.

Note: When disconnecting the fuel hose there will be a drop of fuel come out. Once removed the quick connectors will seal shut so fuel will not drain out.

Warning: When the modified fuel cap is installed and the hose is disconnected from the fuel cap, the generator will not vent. The external tank when connected act’s as the vent when the vent on the external tank is open. This is why you need two fuel caps, one modified and one original. This allows you to disconnect the external tank and use the generator in normal condition.

Note: Since fuel might remain in the external fuel tank for long periods you will want to keep the fuel mixed with Sta-Bil fuel stabilizer in the external tank.

Warning: Make sure that the generator, fuel hose or external tank NEVER SIT UNVENTED for long periods of time. If the vent on the external tank remains shut in hot weather, the fuel will expand and pressurize the fuel tanks causing fuel to be pushed out the generator fuel cap where it threads on to the generator.

Also; if you use the double quick connector method on the fuel hose, the fuel hose when disconnected from the fuel tanks at both ends will have fuel trapped inside. This is normal which keeps the fuel in the hose so you will not lose the vacuum when you disconnect or connect. You don’t want to leave it disconnected in hot weather for very long. Again this is with the double quick connector method.

I have used this system for two years now and it has worked great for me. This season I installed it in my tongue box and took it to Glacier National Park and the Oregon Gathering traveling over 2600 miles.

I can also take it to my storage facility and use it there when working on the trailer without the worry of having to refill the gas tank all the time.

Thank you for posting the concise directions for making your fuel tank. I think even I can follow them with out more than 2-3 backtrackings! Have been thinking of propane conversion but this would sure be a LOT easier!
Thanks again, Chuck H.

Read through this thread from one of the Casita forums. What zig did with his Casita was replace the 20 lb. propane tanks with 30 lb. tanks, but one tank has been converted to be an external gasoline tank for his tongue mounted generator. Boy, some folks think of some very original ideas. Tom Trostel

http://www.casitaforum.com/invboard/index.php?showtopic=1987

One potential problem I see with this is checking the oil. How often does the owners manual recomend that the oil level be checked? What if the oil level gets low because the generator have been running for a very long time?

-- Dan Meyer