Concerning installing a new vacuum shutoff on an MW fuel injection pump.
People do it without the top cover off as in this picture which shows where the vacuum shutoff arm is actually supposed to go.
The 2 pictures are with the bent arm of the vacuum shut off in the correct position.
http://www.peachparts.com/shopforum/attachments/diesel-discussion/111991d1369603068-ip-fuel-shutoff-shutoff-rack-relationship-1.jpg
http://www.peachparts.com/shopforum/attachments/diesel-discussion/111992d1369603118-ip-fuel-shutoff-shutoff-rack-relationship-2.jpg
And even if you think you have done it correctly it is advised to have a way to shut the engine off usually done by blocking the air going into the engine. But you have to plan ahead for that.