Check out Jetpilot's reply in the topic: No cross feed, 727-100x crashed.
The link to the reply --> http://www.captainsim.org/yabb2/YaBB.pl?num=1247894913/0#2

I'm sure it will help sort out your problem. It did mine.

Mark

Here is a quick look at the 727 fuel panel...


The top picture shows tank 1 feeding all engines.
The cross feeds (x-feeds) are all open.
The boost pumps are ON in tank one (amber low pressure lights out).
Tank 2 & 3 boost pumps OFF (amber low pressure lights on).

Note: The arrows on the graphic are pointing to the x-feed valve knobs. Each x-feed knob is black with a white line that will match the lines of the x-feed manifold that are represented on the fuel panel. When the lines match up with the lines on the fuel panel the x-feed is open for that knob. Just to the top of each x-feed knob is a BLUE in transit light. This light is lit only when the valve is moving. If you move the x-feed knob from closed to open, the in transit light comes on while the valve moves to the commanded position, then goes out. If the light remains ON, the valve either failed to move or did not go all the way.

In the lower picture I am x-feeding all engines from tank 2. This is the procedure I outlined in another post, where after takeoff when there is more fuel in tank 2 than in 1 & 3, x-feed all engines from tank 2 until all equal, then go back to tank-to-engine. This is to maintain CG balance.

All boost pumps on in tank 2, [low pressure lights off] all x-feeds open and boost pumps off [low pressure lights on] in tanks 1 & 3 until all tanks are equal.

Don't turn off the engine fuel shutoff switches noted in RED on the lower picture.

Lou