PEVR Test?


New Member
Oct 29, 2002
I'm trying to verify that the PEVR I obtained is working OK. I applied 15 lbs of vacuum from a hand vacuum tester to the manifold side of the valve. It held OK, so the diaphragm should be good. Then I tried to blow air through the one of the top ports on the carb side at a steady rate. My cheeks puffed up and the air passed through to the other port OK. When I released pressure, the air still kept coming through and I couldn't notice much difference, but my cheeks collapsed slowly (No crude jokes, please! I've already thought of all of them!) as I continued to blow air. Does that seem OK? It seems as if vacuum on the manifold side only changes the back-pressure on the carb side slightly, but does not cut it off completely. Is that what I should expect if it's working correctly?

I believe the proper operation is to block flow when the manifold is under PRESSURE.

When you let off the throttle, there is a brief a period of time that the intake is still pressurized but the carb is seeing vacuum. This would suck the power valve closed (and lean the mixture) if PEVR didn't cut off the vacuum.
So I should pressurize the manifold side, then try to draw vacuum through the carb side?

That didn't seem to work. Can't tell a difference in flow on the top side. Might be bad!?

Since it didn't work, I decided to take it apart. I hacksawed it carefully at the bottom of the plastic part in case I was able to epoxy it together again. The port below the diaphragm appears to be clogged with rust or carbon deposits so no pressure is getting through. I've been working on it for some time now, and getting some of the gunk out, but not much luck creating an opening to let the pressure through the bottom. I'm also wondering which way the spring and check plate go, since it popped apart. I'm wondeing if there isn't another automotive vacuum check valve that will do the same thing rather than using the three pressure switch arrangement on the website.