FYI The PO may have bypassed the coffee can reservoir because it leaks.

The line to the PCV may be on its on vacuum port on the manifold. The PCV should be located in the rear, top of the valve cover. You can google that one...

The evaporator system captures fumes which would otherwise vent to atmosphere. It will not hurt performance to cap the fittings. Having the system intact and working will help maximize fuel economy. It doesn't cost anything to fix but a bit of hose... If you don't want to use it cap the feed line from the fuel tank as well so you don't have fuel vapors leaking into the engine compartment. Assuming they are in good order, your fuel filler caps will keep your tanks from over pressurizing.

 

The coffee can reservoir holds a vacuum long enough for me to shut the engine off, climb out of the cab, open the hood and pull one of the fittings off to check for vacuum. I removed it and inspected it just to make sure it wasn't rusted out, it's in good condition on the bottom and on the top.

The PCV is the crankcase breather, right?

I did some research on the evap system, and it looks like I'll need a canister purge valve as well. I'll double check, but I'm pretty sure it's missing. How many MPG do you think I'll lose if I leave it unhooked?

Thanks!

 

PCV = Positive Crankcase Ventilation. On these trucks it includes a breather in the main engine filter housing and a PCV valve with a line running to the intake manifold. On the 4.9 straight 6 the breather attaches at the forward end of the valve cover and the pcv is at the rear. On the V8's the breather is forward on the driver side valve cover and the PCV valve is rearward on the passenger side valve cover.

If you are missing the purge solenoid you will need to locate it's wire harness as well to hook it back up. You may not even loose a whole MPG... I really don't know.