Just as an FYI for all - I had the opportunity to open up the old mechanical fuel pump on my mitsu 2.6l and I took some pictures to show how it goes together internally. Surprisingly, BOTH outlets get fuel from the same chamber, meaning the float bowl line sees the same pressure as the accelerator pump/fuel return line. I always suspected they were hooked to the same place, and I confirmed it.

If you're interested I have posted the pictures at http://digitalpics00.no-ip.org/~halatos/Mitsu_Fuel_Pump

Chris