2000 4.0L OHV VMV
 

I am checking the vapor management valve on a 2000 Explorer using a hand vacuum pump, and find that the small port won't hold vacuum. This is the port that's connected to manifold vacuum via a small plastic tube. Is this normal, or one of my leaks?
Thank You,
fastvee

RE: 2000 4.0L OHV VMV
 

I took the valve apart to find the small vacuum port has only a very small orifice at the bottom. I believe it's purpose may be to purge all vapor from the solenoid area for safety. So it is a vacuum leak, but much smaller than first thought. Can anyone confirm?
Thanks,
fastvee

RE: 2000 4.0L OHV VMV
 

Must be a hole in the diaphram or in the housing. This port should hold vacuum, as it pulls the diapham off the seat in order to pull vacuum on the evap system.

RE: 2000 4.0L OHV VMV
 

I can't find a hole in the diaphragm, but I now have a better idea how the valve works. There is vacuum on the small port at all times that there is manifold vacuum, but it doesn't move the diaphragm to open the valve until the solenoid is energized. When the solenoid is not energized, the vacuum sucks air through the hollow rod of the solenoid, and the tiny orifice inside the small port limits the amount of air it can admit. The plastic cap on the solenoid enclosure contains a foam filter for the hollow actuator rod. The airflow through the solenoid may perform a purge function in case of a valve failure that would leak fuel vapor, but that's just a guess. I have no doubt about the VMV's integrity now, and I have an explanation for why I couldn't pull a vacuum on the small port with my hand pump. Thanks oldtimer35.
fastvee