relay for water injection

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=95161
Printed Date: May 06, 2025 at 3:56 PM

Topic: relay for water injection

Posted By: graemesimpson
Subject: relay for water injection
Date Posted: June 27, 2007 at 9:58 AM

Hi People,

I am about to embark in installing Water Injection system to my car, part of this system is using a "Surflo Water Pump", this required a 12volt ignition feed.

Obviously I will be putting a fuse on this line, but was wondering if it would be better to put a relay in the system or just wire direct to a switched ignition feed ??

If using a relay, how would I wire it into the circuit.

Many thanks

G

Replies:

Posted By: KPierson
Date Posted: June 27, 2007 at 11:17 AM

How much current does the water pump pull? Where will it be mounted?

If it pulls under ~10A and is mounted in the engine compartment I would probably hardwire it.

If it pulls more current, and is mounted in the trunk, I would run a dedicated wire directly to the battery and use a relay.

The relay would be wired like:

Pin 85 - Ignition
Pin 86 - Ground
Pin 30 - Fused battery power
Pin 87 - Water pump output

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Kevin Pierson

Posted By: hotwaterwizard
Date Posted: June 29, 2007 at 11:35 PM

Which Pump?

https://www.shurflo.com/pages/Food_Service/water/categories/deliverypumps/main.html

8005-243-250
12 VDC Delivery Pump w/Bypass
12 VDC, 1.0 GPM open flow, 60 PSI Demand Switch, w/45 PSI Internal Bypass,
3/8" NPT-Female ports, NSF Listed, UL/CSA recognized.

2088-554-144 Delivery Pump
12 VDC, 3.5 GPM open flow, Santoprene® valves, Santoprene® diaphragm,
45 PSI Shut-off, 1/2" MPT Ports, NSF listed

100-000-20 Single Fixture Delivery Pump 12 VDC
without motor enclosure, 3/8" hose barb ports, 1.0 GPM open flow

2088-554-144 Delivery Pump
12 VDC, 3.5 GPM open flow, Santoprene® valves, Santoprene® diaphragm,
45 PSI Shut-off, 1/2" MPT Ports, NSF listed

Here is a Diagram You can ommit the resistor and Led if you don't want a light to let you know when it is on.

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !