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  #1  
Old 07-16-2003, 04:16 PM
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Default Is a relay needed with a Holley blue?

Just went to their website and said the motor draws 3 amps recommends 7.5A fuse. Do you need a relay. People with experience or electrical background please reply.

Thanks,
drag-n
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  #2  
Old 07-16-2003, 05:11 PM
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No just run 14ga or better wire and if you run an aux switch make sure it will handle to load
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Old 07-16-2003, 08:27 PM
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Biggrin

I agree with 23T, That size wire and a properly rated switch will be fine. The reason for the fuse being 7.5 and the current draw only 3 is the pump motor will draw more than 3 amps on start up. The 7.5 will cover the load as the pump motor snaps on.
Also for safety purposes, mount your fuse as close the the 12 volt source as possible that you use to supply the pump. Any part of the wiring that short circuits before the fuse will burn up.


BB
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Old 07-16-2003, 09:43 PM
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23t is right on the money. don't forget to use a regulator with that blue pump.
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Old 07-16-2003, 10:26 PM
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I would honestly run a relay, so the switch isn't dealing with any of the current load. I would also run a minimum of 10g wire.
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Old 07-16-2003, 10:38 PM
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Quote:
Originally posted by ehostler
I would honestly run a relay, so the switch isn't dealing with any of the current load. I would also run a minimum of 10g wire.
The 10ga wire is better( 14 or better) but it all depends on the length of the run as far as relays they are great, but if you use a high quality switch it can cut done on the over-all $$

Just my thoughts and experiences
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Old 07-17-2003, 12:17 AM
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I'm using a relay on my carter super pump. The thought of using a switch was never considered.

Certainly there are many switches that can handle the load. I have used switches on such things in the past.

I would agree with ed and use a relay. Why? Because the fuel pump runs all the time. May be a little much for a switch. Relays are better made for continuous duty, than switches.

Not flaming anyone, who says use a switch, I'm just saying I wouldn't.
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Old 07-17-2003, 01:12 AM
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are the regular automotive relays from radio shack fine?

http://www.radioshack.com/product.as...5Fid=275%2D226
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Old 07-17-2003, 01:35 AM
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That relay should handle the job with no problems.
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Old 07-17-2003, 11:03 AM
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A relay is a good idea,but we've never used one with the Holley pumps.I don't use one for the fact if there is a problem at the track,that is one less thing to go wrong and troubleshoot,especially during eliminations.
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Old 07-17-2003, 08:13 PM
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Quote:
Originally posted by dave571
I'm using a relay on my carter super pump. The thought of using a switch was never considered.

Certainly there are many switches that can handle the load. I have used switches on such things in the past.

I would agree with ed and use a relay. Why? Because the fuel pump runs all the time. May be a little much for a switch. Relays are better made for continuous duty, than switches.

Not flaming anyone, who says use a switch, I'm just saying I wouldn't.
Dave I'm why run a relay on a un-switched elec load? Is'nt that just extra wiring, you have to run the load wire to and from the relay and extra wire for the relay to kick in. Am I missing something?
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Old 07-17-2003, 09:37 PM
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Default Ignition key

I bet he has it wired into a key switched source
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  #13  
Old 07-17-2003, 09:59 PM
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i recommend a relay on any electric pump. i bet ya if you check free flow with a relay and without there will be a difference on free flow per minute
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  #14  
Old 07-18-2003, 12:43 AM
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a BINGO for C318cuin

I turn on the key and the pump runs.

Perhaps it's just a different mind set. I work a on a lot of fi cars. They all have relays for the fuel pumps.

Then again, maybe I just don't want to be confused by another switch on the dash.

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  #15  
Old 07-18-2003, 09:45 AM
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Relay..wouldn't consider installing any E pump without a relay
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  #16  
Old 07-19-2003, 12:17 AM
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If you want to wire the fuel pump to a key switch, I'd use a relay to avoid loading up the key switch with too much current. I believe the "ice cube" relays that Radio Shack sells are Potter & Brumfield (Siemens) which is pretty good. You have to be careful with electrical components from Radio Shack. Some of it (like their toggle switches and push buttons) is pure crap.

I would not hesitate to use a high quality name brand rated toggle switch for a fuel pump without a relay. Brands like Eaton (Cutler Hammer), C&K, Honeywell, SPC, etc. all make robust industrial rated bat handle toggle switches which should work fine. In fact, I think the main reason people have been using relays for fuel pumps is because the auto parts, hardware, and Radio Shack stores just do not carry high quality robust switches that will carry a moderate amount of current. If you really want to get carried away, buy a toggle switch that is mil-spec rated:
http://www.newark.com/product-detail...D121/4905.html

Newark Electronics is a real good source for about any electrical component you can imagine. I think there catalog is about 2000 pages long.
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  #17  
Old 07-19-2003, 12:52 AM
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Quote:
Originally posted by dartgt340
i recommend a relay on any electric pump. i bet ya if you check free flow with a relay and without there will be a difference on free flow per minute
No but if you supply the rigth volts and amps to a e pump how does "it" know if it's direct connect with Con-Ed or a hot 12 v battery or if a relay is in line?
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  #18  
Old 07-19-2003, 02:28 AM
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$16.50 for a switch or $6.00 for a relay...

Another thing to take into consideration is that with a relay, I can safely run a 14g or smaller wire from a switched power source to the relay and a 10g feed from the relay to the fuel pump, instead of a 10g lead from the switch all the way out to the pump.

if you are using the recommend (by Holley) 7.5A fuse, you will need a minimum of a 12g lead (10g recommended) to the pump, if you want the fuse to burn out before the wire melts.
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  #19  
Old 07-19-2003, 08:58 AM
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Quote:
Originally posted by ehostler

if you are using the recommend (by Holley) 7.5A fuse, you will need a minimum of a 12g lead (10g recommended) to the pump, if you want the fuse to burn out before the wire melts.
The wire will not melt at 7.5 amps. The reason for the larger size wire is because of voltage drop/total wire length.
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