It's strange, because the fuel in the filter and line will actually run back to the tank. (It's a clear plastic filter, so, I can see that it is empty.) Is there supposed to be some sort of check valve, or ball that stops the fuel from running backwards into the tank? I'm guessing that there should be something to keep the fuel in the line. Quite possibly the line is pulling air in because of one of the carbs?

The engine was swapped about 20 years ago, so, there is a chance that the part that is missing was not swapped over from the donor car.

It's has 2 4 barrel carbs on it.

Any thoughts, comments, suggestions?

-Ted

A couple of things, Ted:

1) First, your car has two two-barrel Zenith carbs, not four barrel. They look big but are not. Unless of couse you have done a marvelously creative carb/manifold swap/fabrication project. Probably not too likely...
2) The fuel return valve on the front carb may be sticking in a dramatic way and allowing the fuel to siphon back toward the tank. It will not allow the carbs to drain since they have needle valves at the floats that regulate the fuel inflow, and an air gap in the carb that breaks any potential siphon. Depending on the condition of the fuel pump valves this siphon may empty the line from the carb to pump or farther on back. Slight chance of this...
3) Most likely cuplrit is the fuel pump itself. There are two valves, inlet and outlet. The inlet valve allows fuel into the pump from the tank when the diaphragm moves up to draw it in, and then it closes. The outlet valve opens when the diaphragm moves the opposite direction to force the fuel to the carb. Both valves need to seal tightly so that fuel cannot leak past. Probably leaking pump valves.

Old pumps could be opened and cleaned, diaphragms and springs replaced and/or the valves could be re-seated with abrasive valve lapping compound, a very short term fix. Newer pumps are sealed with a crimped lid that cannot be serviced, just replaced.

I would replace the fuel pump if it is more than a few years old.

For what it's worth...

230/8