How do you shut off a diesel?

[Ganaraska]

1985 300SD won't shut off on the key, have to get under the hood and push the stop lever. I have Mitchel and haynes manuals on CD but neither help much. Also have looked at the vacuum diagrams on this site but they are pretty vague too.

So far as I can make out, on the injection pump the front section feeds the fuel lines, the middle part is the shutoff and the back part is a vacuum control for the transmission etc?

The motor was recently rebuilt and the mechanic may or may not have got the lines back on right. I suspect not because there is a brown and blue plastic line coming out from the firewall that's not hooked up to anything. Can't find a place for it either.

Can anyone explain the shutoff and how it hooks up?