My friends 80 240 d will not shut down. This should be any easy diagnosis since he is not utilizing any of the yellow or green vac hoses. The vac locks are not in operation as far as I can tell.
Only the brown vac hose going into the dash( to key?) and brown coming out (from key) going down to the IP shutoff are pulling vac.

Here is what works.... I pulled the hose of the IP shutoff and put on a test hose and as soon as I create vacuum by sucking on the hose she shuts down.

Here is where it gets strange... the hose I pulled off the IP shut off is pulling plenty of vac when teh key is turned off... when I put my tounge on the end it pulls real hard. when I put it back on the IP shutoff and turn the key off it will not shut the IP off.

any suggestions

Thanks for the reply... one more thing though.. When I stuck my tounge on the end of the vac hose and turned it off, I nearly got a blood blister on my tounge. That baby sucks.. pun intended!

most likely the key perhaps?