relay for water injection

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

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 - GroundPin 30 - Fused battery powerPin 87 - Water pump output

Kevin Pierson

Which Pump?

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

8005-243-250

12 VDC Delivery Pump w/Bypass12 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 Pump12 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.

John DeRosa (Hotwaterwizard)

Stockton California

When in doubt, try it out !