Backup Fuel Level Indication

[Pura Vida]

93 Mariner 330 - one fuel indicator with P/S selector switch...I found the indication a bit inaccurate & unreliable. In addition, had reason to believe that the port & stbd were reversed - I was right, but easy fix, i simply rotated the switch 180 degrees and marked the new "top" of the switch to ensure future readings were accurate.
Still unhappy with less-than-certain fuel levels, i came up with a cool solution. I will try to post pictures.
-painter's masking tape
-standard 2-part epoxy, clear, ~ 30 min working time
-approx 1 gram of thermochromatic pigment. My selection changes from black to yellow @ 88F/31C. (bought 10 gram container, but only used a tiny amount.

On each of my two aluminum fuel tanks, I laid vertical masking tape ~ 1" spaced. Mixed the pigment into the 2-part epoxy. Painted between the tape. Removed the tape to leave a 1-inch wide strip of pigmented epoxy.

After curing, i now have a black strip on each tank. I spray hot water on the tank for ~ 15 seconds until the epoxy turns yellow. A few seconds later, since the fuel is cooler, the fuel level quickly turns black again showing the fuel level.
My stbd engine heats the hot water tank, and with the cockpit shower, this is quick and easy. Doesn't even take much water - maybe 1 quart (which goes to the bilge).

I think i was able to post pics of the pigment (amazon), and the resulting color changes after hot water. Seems they may be rotated and out of order, but still useful.

If someone were to try this, i think my temperature selection was good for my area, maybe warmer climates may need higher activation temperatures. I bought the 10 gram size, probably enough for 50 tanks...although it is cool and you can find other uses for it, certainly don't need the 10 gram size.

[Pura Vida]

A side note - had some extra pigmented epoxy, so i dabbed spots on top of each thermostat and the hoses from it...this gives an indication of when the t-stat opens.

[Viper]

That's thinking out of the box!

[plittle2005]

Genius!

[tomschauer]

Great work, but darn, that is lot of effort to check fuel levels!

[RobGunn]

You can get self adhesive tape from RV parts suppliers that will do the same. Its made to put on the side of LP tanks but it will work the same on a gas tank.
One other fuel tank level test that I trust is simply open a access plug on the top of my tank and insert a 1/4" wood dowel rod from the hardware store. I will always trust my dowel rod over my gauges.