Fuel tank questions

[Jim Rosenthal]

Interesting thread...I am opting for two separate systems, essentially, with no balance tube. As Bob said, a balance tube low in the tank means that fuel in that pipe is always under pressure. Sooner or later it will leak.
The Mark V cars use three tanks- the two sponson tanks, which drain into a common feed tank, I think. These setups are not such a problem on carbureted cars but on EFI, where you have to send fuel BACK, it needs to go where it came from...
Another weird item on a lot of GT40s is that the fuel pumps are plumbed in SERIES !!?? Go figure. Why would anyone do that? I am still trying to figure that one out.

I plan to use two tanks, two senders, two gauges, two pumps- switched so that power can only go to one side at a time. We'll see how it all works.

 

[Trevor Booth]

Jim,
and two check valves. Dependant on pump (and I never trust them) you can pump fuel back through them. If you study carefully photos of Orig units you will see what looks like a glass bowl filter after the twin pumps. This is a fuel regulator and filter and can be sourced from Alfa's. I had a problem many years ago with a twin pump setup with fuel pumping back through the check valves. With the pumps (SW) running at 2.5 psi it was not enough to close the check valve 100%. I bumped the pressure up to 5psi which stopped the leakdown but that would have been too high for carbs. I added a separate regulator at 2.5psi with pumps at 5psi --Problem solved. I presume that ford struck the same problem.
You might also consider wiring pumps through an oil pressure switch or inertia switch and also have the ability to run both pumps. With two occupants it is better to draw from both tanks simultaneously.
Cheers