12V vacuum pump
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Mountain Pass
Joined: Aug 2003
Posts: 101
Likes: 1
From: california
12V vacuum pump
How much vacuum is that little pump supposed to pull?
Google says 17-20" That seems low for pulling in hubs and everything its connected to🫤
Everything's working fine, the 24mo. old doorman crapped out so I revived my original..
My Question is;
What is the Cutout Specification ?
I set the cutout at 15 inches, just below the pumps max negative pressure, but I'm not finding any OEM spec.
Google says 17-20" That seems low for pulling in hubs and everything its connected to🫤
Everything's working fine, the 24mo. old doorman crapped out so I revived my original..
My Question is;
What is the Cutout Specification ?
I set the cutout at 15 inches, just below the pumps max negative pressure, but I'm not finding any OEM spec.
Last edited by robert kelsey; Jan 21, 2026 at 03:35 PM. Reason: Clarification
Cargo Master
Joined: Apr 2012
Posts: 2,029
Likes: 530
From: Bottom Of Pikes Peak
I do not have an answer but I believe the hubs only require 6-7psi...not sure what that equates to. If you have a handheld mity vac, the hubs actuate quite easily from what i recall.
What are you trying to accomplish exactly? Are you looking for a cheaper alternative for a pump?
What are you trying to accomplish exactly? Are you looking for a cheaper alternative for a pump?
Tuned
Joined: Feb 2025
Posts: 298
Likes: 236
From: Brighton, IL
Why? Do you feel your vacuum pump is running too much?
The dash heat, floor, defrost blend doors don’t take much and the ESOF is not a steady vacuum….. it is a pulse vacuum. It takes slightly more to engage (lock) and a bit less to disengage (unlock)
Heres what I’m coming up with:
“8.75 (in. Hg) to lock and 5.9-7.1 (in. Hg) to unlock”
IMHO, if your trying to regulate the pump you should be looking for leaks, which will cause the pump to run excessively (faulty hose, etc.). Regardless of what the output of the pump is……it will quit running once the system and its vacuum reservoir is drawn down to the preset vacuum (whether lower or higher than what you have) until something bleeds off the reservoir and the vacuum pump kicks on again.
i had a vacuum pump that was running a lot and I could hear the increase in cycles (noise). An inspection found that the vacuum hose to the right side knuckle had come off. As soon as I trimmed it, and reinstalled it the vacuum pump shuts off in very short order.
The dash heat, floor, defrost blend doors don’t take much and the ESOF is not a steady vacuum….. it is a pulse vacuum. It takes slightly more to engage (lock) and a bit less to disengage (unlock)
Heres what I’m coming up with:
“8.75 (in. Hg) to lock and 5.9-7.1 (in. Hg) to unlock”
IMHO, if your trying to regulate the pump you should be looking for leaks, which will cause the pump to run excessively (faulty hose, etc.). Regardless of what the output of the pump is……it will quit running once the system and its vacuum reservoir is drawn down to the preset vacuum (whether lower or higher than what you have) until something bleeds off the reservoir and the vacuum pump kicks on again.
i had a vacuum pump that was running a lot and I could hear the increase in cycles (noise). An inspection found that the vacuum hose to the right side knuckle had come off. As soon as I trimmed it, and reinstalled it the vacuum pump shuts off in very short order.
Last edited by Big Horn 2; Jan 21, 2026 at 03:13 AM.
Lead Driver
Joined: Dec 2006
Posts: 7,093
Likes: 147
From: San Diego, CA
It will work as intended when there are no leaks so vacuum level is not the issue as much as leaks which result in excessive/constant running.
The pump is not designed for continuous operation which is why there's a large reservoir next it to "store" vacuum for operation. The pump should only run intermittently to maintain vacuum level in the reservoir. If your pump is cycling a lot or running continuously that will result in an early grave for your pump...and it's not pocket change to replace (I have that t-shirt).
The pump is not designed for continuous operation which is why there's a large reservoir next it to "store" vacuum for operation. The pump should only run intermittently to maintain vacuum level in the reservoir. If your pump is cycling a lot or running continuously that will result in an early grave for your pump...and it's not pocket change to replace (I have that t-shirt).
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