Fuel system diagram

[JimC]

In Ernie's diagram for the pre-'74 Skymasters (http://www.consultresearch.com/337fuel.htm) he clearly shows the electric pump BEFORE the fuel selector. In this case, the electric pump can only pull from the main tank.

In my T337E manual, it clearly shows the electric pump AFTER the fuel selector. In this case, it could pull from whichever of the 3 tanks is selected.

As he says on his fuel page, this has serious consequences if you run a main tank dry - you won't be able to draw fuel from the aux tank if the electric pump is before the fuel selector.

Aside from running my mains dry (over an airport) or disassembling the system and tracing each fuel line, is there a way to tell which system my plane has?

One thought I have is to run an engine dry on an aux tank, and then switch that engine to crossfeed but turn on the dry engine's pump. For example:

1) Run the front engine dry on the front aux tank
2) Switch the front engine to the rear tank
3) Turn on the front elec pump. If the pump is BEFORE the selector, the engine shouldn't restart. If the pump is AFTER the selector, the engine should restart.

Thoughts?