heated fuel tank

The copper coil carries hot engine coolant into and out of the tank. Heated coil in tank
outboard motor fuel tanks, make cheap SVO tanks

Here's a cheap way to put a heated coil into an SVO tank without cutting holes in the tank and sealing them back up. This only works if the fuel tank has a cap that comes off with a quarter turn.
In a straight vegetable oil (SVO) fuel system, the heated fuel tank is the biggest cost variable. From a very expensive custom tank on down.
I found this 1970s style tank. It fit so well I had it patched and sealed ($90). I was given three later model fuel tanks (which don't leak) they will probably be easier to convert and make even better SVO tanks. The coil won't have to go through the cap. I'll show you when it's done.