Gx390 gas tank upgrade


I believe i seen it on here before but cant find it. Not trying to go crazy on this but is it possible to add a separate tank of gas for a gx390?
I swear i seen a cap to screw onto the top of the existing tank to siphon in more fuel from another tank.

I plan on getting a 8 gpm hot water machine next year so not a big deal.


Was it this?


No but that is a idea.


Ive see other guys add remote tanks for those machines but i couldnt figure out how. So i saw that gavity fed aux tank, put it higher (dont even have to) and solved my problem.

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I’ve got this on a ryobi generator. Never seen a cap conversion for the little Hondas with the big silver caps


I think that is what i seen. Darn i thought it would fit


You can use a fuel pump and have the remote tank on the deck of your trailer if you wanted. All you need is a pulse line. You can get a pulse by drilling a hole your valve cover and installing a hose barb. You can also get a pulse by installing a barb in the carb insulator. I used the insulator on an 18 hp I installed in our golf cart. I have also done the valve cover mod. Both work the same.

Here’s a link to an carb insulator that already has a barb installed.



Hi Grizz. I was running into the issue of running out of fuel while I was working. Very frustrating!! I built this system myself, and it works outstanding.

A used boat engine gas tank, fuel line from an auto parts store, valves from Home Depot and a flange produced by ,”Banjo”.
I built the tray out of aluminum and secured it with stainless steel hardware.
Hope this helped.


My head hurts so much right now


Bahaha! That can’t be unseen now. The level of professionalism in this group just keeps getting set higher and higher every day…

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Your comment actually made me crack up… people looking at me like im some kind of weirdo

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I’m actually considering mounting a 20-30 gallon fuel cell under my Sprinter and running it to both of my 670’s (yes, they’re ancient, but they can’t be killed). The fuel pumps on them might not be too happy though if I do.

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This industry will never be seen in a professional light by customers as a whole when this is what image is portrayed by many.


I think i will go with your post. No offense to anyone else :joy::joy::joy:. Like i said i plan on buying a 8 gpm next year but i want it to atleast look clean and professional. Thanks marine. Is this something fairly easy to install or is this something im better off having someone more mechanically inclined do.


I’m not gonna lie… I dig the ingenuity. But why so many valves?

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Uh, because more valves = more fun. Silly Squid


Btw brodie. I pulled the trigger on a Acer cromebook 15 today. 1080 hd touch screen 15 inch screen smooth and faster than i expected. Im pleased with it.


This may work for your application


Most any fuel pump in a gravity feed situation is going to flood the carb