What car, what system, would be nice. Really depends on the depth of answer you wish. Based on your confusion I can see my first answer was suitable.

There are a few on this site who actually can give answers that depend on what car you are talking about. The fact you have atleast two vacuum pumps on that car DEPENDING on what it is, means decent questions will get decent answers.

If you don't know that you need to describe your car and system in technical questions maybe your post shouldn't be on a technical forum. Try dear abby.

BTW, I moderate the tech only section and then only as a volunteer. I don't owe you anthing!! I am very happy to ignore your posts if that is better for you. I only answered it cause it had dropped half way down the page with no response. I'll do better next time.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician