How to Add an Aux Fuel Tank to a Generator

Most of the household generators have relatively smaller fuel tanks which can provide support up to 2-3 hours at maximum. This can be a bit of a problem if you want to have an uninterrupted supply of electricity. To solve this problem, you can either operate two or three generators in parallel while ensuring that the load transfer is swift or go for the cheaper and one-time method i.e. to increase the fuel holding capacity of the generator by adding an auxiliary fuel tank.

The procedure of adding an auxiliary fuel tank is not that complicated and with proper supplies, it can be done within an hour tops.

Things Required:

– 3.5 gallon or 6 gallon marine gas tank
– 2 marine gas tank fittings (black plastic)
– 2 brass marine fittings for gas tank
– Marine hose w/squeeze ball
– 2 small hose clamps
– Drill
– 0.5 diameter hole bit
– Extra cap for your generator (optional)
– Silicone sealant (optional)


  • 1

    Place your equipment at one common place. Now take one of the brass fittings and connect to the marine gas tank. Make sure that you buy a tank which has a pressure vent system and a special attachment through which you can hook up a line. Any normal marine tank will have these accessories.

  • 2

    Now connect the black plastic connector with the hook up attachment on the marine tank.

  • 3

    The next step is to drill a hole in the cap of the generator tank. Take the cap off and place it on a stable and firm platform. Now place a wooden piece between the cap and the platform and secure it. It would be best if you have an access to a vice.

  • 4

    Fix the drill bit in the drill and slowly initiate the process of making the hole. Remember to go slow and under no circumstances should you use a drill bit of greater diameters. Also keep the drill straight during the entire process.

  • 5

    The second brass fitting goes into the cap opening. If you take care of the dimension, the brass connector should be an exact fit. If it is not, you can use a silicon caulk to shore up the extra space. The second black plastic marine gas fitting goes on top of the brass fitting.

  • 6

    Take the marine ball pump and hose, and with the arrow on it pointing towards the generator, connect the generator and the fuel tank. They should ideally be three feet apart.

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