# Brake pump blowing instead of sucking??



## mvest (Jan 22, 2009)

I have a question? I have a Thomas pump to start with. This did not come with any cut in/cut off switch. Now I'm pretty sure the old ICM had a vaccum/sucking. The Thomas pump has arrows pointing out the flow of air and after I hooked up, I noticed it's actually 'blowing' air out of it. Could someone tell me if this is correct or should it be in a vaccum? Also is there any other cut in/ cut off switch other then the 'big gray box'? Thanks


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## TheSGC (Nov 15, 2007)

There should be two ends to the pump. One is a suction and the other is for blowing air. My vacuum pump is a Thomas and it's actually a vacuum or compressor pump, depending which connection you use.

Here is a picture of my pump connected to the Air Input for a vacuum setup.
http://2.bp.blogspot.com/_ighXUBbIRfk/SSjMgBYLI_I/AAAAAAAAAH4/oJ-zv3ZEwU4/s1600-h/S5001630.JPG


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## JRP3 (Mar 7, 2008)

Could you have it wired backwards?


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## mvest (Jan 22, 2009)

Thanks, I willl check for the wires being backwards. I don't think they are but will check. I will try to post a pict. later. Now, do either of you have a cut on/off switch w/your's? Its a little annoying b/c it runs all the time.


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## dimitri (May 16, 2008)

You must add a vacuum switch via a T-fitting to interrupt pump't circuit. You don't want it running all the time.

Depending on the switch's amp rating, you may need to use a relay, since pump takes about 8-10 Amps, some switches can only handle 3-5 Amps.

Look for "Square D vacuum switch" on Ebay.... these don't need a relay...


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## JRP3 (Mar 7, 2008)

I don't have it hooked up yet but I do have a cutoff switch.


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## JRP3 (Mar 7, 2008)

dimitri said:


> Depending on the switch's amp rating, you may need to use a relay, since pump takes about 8-10 Amps, some switches can only handle 3-5 Amps.
> 
> Look for "Square D vacuum switch" on Ebay.... these don't need a relay...


I never thought about the relay, did you use one on the setup I got from you?


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## dimitri (May 16, 2008)

JRP3 said:


> I never thought about the relay, did you use one on the setup I got from you?


Yes, according to EVParts.com where I bought it, it's rated 4 amps. It could work without relay, but it might have a shorter life...

I used a cheap automotive relay, worked fine....


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## simey_binker (May 13, 2009)

heh heh - sorry, I couldn't resist.

http://www.youtube.com/watch?v=ZXOAc5yt218

Sim

(dang, no HTML editing...)


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