I have had problems on some planes with short fuel lines in a dive. As you surmise, the fuel in the line is the primary source. Typically in a dive, you reduce throttle, which obviously reduces fuel demand. Another trick I've used is to put a loop in the fuel line between the tank and the carb. This provides an additional fuel reservoir. A large fuel filter can also help. In the extreme, a header tank can also help.

Most dives don't last long enough to require a lot of fuel.

Brad