lots of missing vacuums

[sm023595]

Hey guys finishing up a rebuild on a 88 wagoneer, and I can't recall where this larger hose goes. I believe it went into the back of the stock carb, but i've since swapped it out for EFI.



In addition, I found this vacuum port on the intake manifold that didn't have anything going to it. Should it be capped or does something to there.



Thanks

[got the willys]

http://www.ifsja.org/forums/vb/showthread.php?t=189351

I had alot of help going through vacuum issues recently. Here's the thread you may find useful. But mine is not EFI.

[Bob Barry]

That large hose is the suction line for the PCV; it should go to a large port on the throttle-body baseplate. Don't know where that is located on that FI unit.

The other port usually feeds manifold vacuum to the thermostatic controls on the air-cleaner. If you are not using that air-cleaner, you would cap the port.

[rang-a-stang]

The thing with vacuum is little tiny leaks can really affect the way our engines run AND it can be really hard to find those tiny leaks. Sometimes

Here's what I would do:
Plug every single vacuum port on your manifold and throttle body. EVERY ONE OF THEM. Go buy a set of good vacuum plugs and plug them all. Also get some bulk vacuum line. Your engine should run great with NOTHING hooked up to it.

Then, one by one, hook up the systems you HAVE to have. So, pick the biggest nipple on your manifold and use a brand new vacuum hose and connect that to your brake booster. You have to have your brake booster hooked up. Start your truck and it should still run awesome but now have power brakes again. Then use a brand new vacuum hose, hook up the PCV to the second biggest nipple you can find (make sure there is a PCV valve and it works). That nipple should be on the bottom of your throttle body. Your manual that came with the EFI should show what port to use for PCV. Then start your truck and make sure it still runs good. Then take a brand new line and hook up your distributor vacuum can just like it is hooked up on the vacuum diagram on your radiator support. So, vacuum line from the distributor to the 3 port switch on your manifold. Then one line to ported vacuum on your throttle body and one line to a small nipple on your manifold OR throttle body. Then start your truck and take it for a ride. It should run great cold, and it should run great hot.

The last step is to fix the things you want to have one by one. So the vacuum line that goes from the engine compartment to the heater motors, 4wd switching, etc.

I have found that when a vehicle is as old as ours A) the rubber lines are cracked and B) previous owners/mechanics have probably butchered the vacuum lines and where they are supposed to be. It is much easier to just start from scratch than try to fix all the patch jobs over the years.