On my '84 K10 6.2l I vacuum tested the pump and I only get about 3psi vac at the t-connector. Nothing. I also wonder how my EGR valve has been working on low vac pressures. If it doesn't work, temps will rise and cause knocking and rough idling...I guess?

Anyway, is it really important that I get the EGR working and get the vacuum pump vac'ing?

I discovered this while taking out my non-functional cruse control and putting a new accel. cable in.

I'm currious as well. What is the max the vac pump pulled? I bought a extra electric vacuum pump. And will be installing a vac cannister as well.....

The vacuum pump should pull well over 20 inches. As for the egr- get rid of it! See if you can locate a J series intake, much better flow and this mod alone is worth about 15 hp. The egr does a very good job of making the intake ports very dirty, gunking up the intake valves and generally degrading performance.

Where could I procure a J series IM? Can't find anything to do with 'em online.

Keep an eye on ebay, they come up from time to time. Also you might try one of the military surplus places like Boyce. All of the military vehicles come with that manifold.;)

Where could I procure a J series IM? Can't find anything to do with 'em online.
I should be removing mine..........

Removed the egr and trashed the emissions hoses/solenoid harness and like valves. I noticed a better flow into the intake.

I also contacted a guy locally on craigslist about trading my manifold + $50 for his '85 military blazer 6.2l manifold (I presume J series---military).

There is a 6.2 intake manifold on ebay right now with a buy it now price of 40.00. Do a search for 6.2 diesel.:D

In a perfect world a vacuum pump will pull barometric pressure. Most tests show about 28" on the vacuum guage. Test directly at the pump (3/8" hose bib, elbow fitting), not on a hose or t-fitting away from the pump. Some stuff connected to the vacuum system has built-in vacuum leaks and will lower the reading.

You are right but that only applies to sea level. Where I am at 23 inches is max.):h 5000 ft

See what happens when you get your head in the clouds, you're vacuum drops!!):h (huh?)

what's the EGR valve and where is it? I am new to all this but i did notice my vacuum pump seems weak as well and plan to fix it soon. thanks!
Paul

Exhaust Gas Recirculation, if you have one, it will be a pot sitting inside your air cleaner, with a vacuum line running to it. I wouldn't get too upset if it were not working properly, you're better off without it. I would bypass this and the exhaust flap on the driverside completely and dedicate your vacuum pump to operate the vents inside the cab instead.

You can cut off the mounting base of the EGR, weld in a plate to fill the hole, and re-install the base so youwill not have anymore EGR problems. You can take off the intake manifold and replace the gasket with a solid gasket and you will in essence have a j manifold configuration. I also cut out the butterfly in the left exhaust manfold which makes it a j configuration. Later, I replaced my injection pump with the heavy duty pump (puts out more fuel) so I completed my engine to the J configuration.

If you don't replace the intake manifold gasket with a solid one then the cross-over thru the manifold acts as a balance between the two exhaust manifolds. I didn't want the extra heat going thru the manifold duct so I had a muffler shop install a balance pipe between my dual exhausts. That balance pipe does increase the engine torque. My truck hauls a very heavy camper and I can climb hills where I use to have to downshift so it does work. It also made the engine louder at 45-50 MPH, but quieter at 55 MPH and above. Race cars of many years ago use to have them.