I have two vacuum solenoids on the passenger side fender wall mounted one over the other, the bottom one I believe goes to the air valve and the power heat valve, and the top is the purge solenoid.

Can someone clarify which one is the purge( I believe the top one) and the connection locations, the diagram isn't clear(to me) manifold vacuum goes to one an the small line off the canister goes to another, do I cap the third?

 

First off, please put the engine in each post or in your signature so it appears in each post so that we don't have to look it up to help you.

I have a book of 56 vacuum diagrams for the 1st Gens and 3 of them are for 87 318s.

One of the connections should be the vent to allow the vacuum to be vented off when the solenoid switches. I am not positive on yours but most of the trucks have a filtered vent on the passengers side fender and a hose should go to that.