Champion Duel Fuel Generator external tank idea

[Godsgrace]

Hi Everyone. Why can't a tee be put in the fuel line with a shut off valve going to the gas tank on the first part of the tee, the second part of the tee would go to the selector switch, and the third part of the tee would go to the external tank with gravity feed? With the inline valve to the gas tank, the tank could not overflow. Am I missing something here? With the valves installed, the generator could always be switched back to the onboard tank. I think this would work even with the carbon canister. I hope so as spending 10 days at deer camp in Wisconsin, I had to fill the tank about every four hours.

[theoldwizard1]

Expanding one what Matt said ...

Almost all external tank setups use a vacuum operated fuel pump. Typically these are made by Mikuni, but sold under different brand names. Available on Amazon for $20-$30.

For vacuum, they drill a hole in the valve cover slightly smaller than vacuum pulse hose going to the fuel pump. Make sure there is a shut off for the external tank and that you use it ! You might have to start on the internal tank before switching to the external tank.

[Grit_dog]

Matt, good point about the head pressure.
So an avg generator has the fuel maybe 1ft above the carb needle. So less than 1/2 psi of static head pressure. Even if one raised the top of the aux tank another 2’, that would be under 1.5 psi.
Within reason, I don’t think it’s a concern. Given the x sectional area of the needle valve seat opening is probably 1/1000th of a square inch (order of magnitude, not calculated) the overall pressure on the needle will still be minuscule.
Plus most every gravity feed line I’ve seen, the filter (above the carb line inlet) doesn’t fill completely with fuel. But rather the fuel trickles through the line. Seems the fuel isn’t actually placing a solid column of static liquid head pressure on the needle anyways.
Icbw, but I’d bet a bottle of bourbon and a back strap that it works fine!

[Matt_Colie]

Grace,

I'm not just sure where to start here.....

Most of the Champion units are gravity feed top tanks. What that means is that the float in the carburetor is designed to handle just the fuel pressure of the hydraulic head from the top tank. So, if your planned auxiliary tank is taller, it may overpower the needle valve that regulates the fuel level in the carburetor. That could be a disaster.

There are ways to work around this, but none are simple or cheap.

Then there is another problem. These are splash lube engines and so have no lube oil pressure. A quick look says that they do have a lube oil level safety, but you still should be in the habit of checking this regularly.

Best of luck with both the hunt and the generator.

Matt

[Grit_dog]

Just don't get too drvnk at deer camp and switch over to the aux tank and forget to shut off the back flow to the built in tank!

[Grit_dog]

Seems no different than my mowers that have external tanks, valves, tees on the one that has 2 tanks. Switch the valve over and keep on truckin.