I am trying to locate a vacuum leak on my 85 300D. I've isolated it to one of three hoses that go into the firewall. Two are yellow and attach to a yellow plastic piece just before the wall. the other is red and looks a lot like the one that comes out of the firewall and goes to the shut off thingy. All three of these will nto hold a vacuum, or even create on. when i hook a tester up, I can pump and pump and not create a vacuum. one of the yellow ones will hold a pressure though. very puzzling.
My question is what are these for? I am assuming that one goes to the shut off circuit within the dash. The yellow ones I have no idea about. do I need them? can I cap them off? I am doing all this to try to get the engine to shut off when I turn off the car. So I don't think I can just cap off the red one. Any insight would be appreciated.
Have a great day, Bill