I have a 86 dodge van 250. After driving sometimes it will not start up until I give the black box a shake (not sure what the black box is, it's on the fire wall to the right of vehicle). I have replace the box and it still does it time to time. So my question is this a common problem and if so what's the solution?

 

I can't help you specifically since I have never owned a vintage Dodge van, but from the knowledge I have of other cars and truck that box is probably a relay/fuse center. You should open the box up and reseat all the fuses/relays in the box (after you disconnect the negative battery cable of course)
Then I would look at the connections while you are reseating them for corrosion or a connector that is loose. Then I would look at the inside of the cover and/or at a schematic and see which one is your fuel pump relay or ignition relay. It sounds like you have a sticky one.

Good luck

 

Thanks!