What does this thing on a MC2150 do and what should I hook it to?

[luggage]

I'm putting a MC2150 on my eagle (from an 83 Mustang 3.8 ).

What is a Pump Relief Valve and what should I hook it to? It's item #51 on this diagram: http://www.carburetion.com/diags/2150diag.jpg

[Jurjen]

Here is the answer:

http://www.jeeps-offroad.com/showthread.php?t=31892

Hooked up to manifold vacuum.

[luggage]

Simple enough.

[GRONK]

You actually don't need to hook it to anything.  You can simply leave it uncapped if you like or run it to manifold vacuum.  I recommend trying both and reply w/ the difference if anything is noable, but I have set up hundreds of 2150's w/ this valve and have never used it.