How to test vac modulator on A4LD

[stfree]

Hello all,

I'm trying to determine what to expect in applying a vacuum to a suspect vacuum modulator on a A4LD '90 Ranger. Should I be able to pump a specific number of inches of vac and expect it to hold? What I see now is that I can rapidly pump down to about 10" of vac but it bleeds off within 3-4 seconds. I'm connected directly to the device straight off the pump with a known good hose.

Thanks

 

[adsm08]

It should hold a little bit, but it may not hold well since it is designed to be hook to a constant source, and needs to be able to vent quickly.

Usually the test is if you get ATF in the face when you unhook the line.