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Power Hungry Vacuum Pump

Posted: Mon Sep 17, 2018 5:47 pm
by charliejuliett
Since tossing my OBC, I have been closely monitoring my 12 VDC draws on the car since I now only have 36 amps to work with. According to canion my single largest load was the vacuum pump. I decided to look up the recall information and replace the pump since this recall was never performed on my car. (part#4641a032, 150$ on ebay) I included the service bulletin and some pictures of the old vs new pump current draw. The old pump sucked up 26 amps while the new one draws about 14, or roughly half. I thought this was a neat data point to share.

Here is a link to the recall instructions and some pictures:

https://drive.google.com/drive/folders/ ... sp=sharing

Re: Power Hungry Vacuum Pump

Posted: Mon Sep 17, 2018 8:23 pm
by ed5000
I wonder why the old pump drew so many more amps.

Thanks for sharing.

Re: Power Hungry Vacuum Pump

Posted: Mon Sep 17, 2018 8:54 pm
by JoeS
charliejuliett, thank you for making those measurements and posting the pictures. BIG difference between the two (not addressed in the recall notice).

Re: Power Hungry Vacuum Pump

Posted: Tue Sep 18, 2018 10:43 am
by jray3
I'm slightly confused in that page 12 of the safety recall bulletin shows the 2010-12 vacuum pump that was recalled to be all-metal construction, matching the photo of charlijuliet's replacement pump. Later pumps have a black plastic housing, which is what's in my car (and the spare that I salvaged). Is this our determinant; aluminum housing=bad?

Re: Power Hungry Vacuum Pump

Posted: Tue Sep 18, 2018 1:29 pm
by charliejuliett
On page 14 of the recall bulletin it states the replacement pump has a black motor covering and a plastic housing. So I actually replaced my unit with the recalled style! :shock: Well I suppose will keep the old pump if this new one acts up...

Re: Power Hungry Vacuum Pump

Posted: Tue Sep 18, 2018 1:50 pm
by jray3
Sorry to bear bad news, charliejuliet, but the higher amp readings may show that your original pump was already struggling against some corrosion! A pad of filter material banded around the exhaust port might reduce the salty spray getting in there...
I've long wanted to add a rear belly pan for improved aero and less dirt in the motor bay, but that's waiting until after a proven battery charger cooling fix.

Re: Power Hungry Vacuum Pump

Posted: Thu Oct 17, 2019 12:02 am
by 1kaspars
Does anyone have info about brake vacuum pump cleaning, dissasamble? Last option is to replace pump, but want to fix and see the problem before.

Yesterday I compared my and friend's I-MIEV's vacuum pumps:

* by sound one of them was slower;
* by OBDLink LX + Canion power draw from battery was ~ 276w VS ~458 watts (slower one by sound).

Measured power is differrence between car ready state power draw (~0,6 A @ 340V) and working vacuum pump (for example 1,2A @ 339V).

For precise measurements it would be useful to measure 12V current draw, but it is obvious that measurement with OBD + canion showed significant difference.

From recall bulletin: "Due to the location of the brake vacuum pump exhaust hole, mud containing road salt could enter and adhere to it,
causing the exhaust hole to be blocked from corrosion of the aluminum portion."