#1 is the shutoff valve. applying vacuum to that will shut down the engine.

#2 goes to #15.

#11 is the return fuel flow back to the tank.

#12 is the return from the injectors.

#6
is the egr activation switch (i think). It is FOR SURE related to emissions and should just be left there unhooked. Ignore it.


#7 is a temperature probe or switch. You probably wont need it.

#5 is the main fuel supply.


#4 goes to #14

#13 goes to #3


#8 is just a good place, in your case, to tap vacuum. I beleive its real purpose is to supply vacuum to the emissions systems and the transmission vacuum modulation for shift smoothness.


#9 should just be considered another good place to tap vacuum, but beware it has reverse flow direction (they used this to make sure the in-cabin vacuum systems that were hooked to that nipple wouldnt drain back vacuum with the engine off). if you need vacuum for anything in cabin or for your improvised engine shut off, these are the places to get them.

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1981 300SD 512k OM603