Archived pusher pump installed...electric ??

[Larry Willard]

I installed my pusher pump today, but as soon as the fuse is put in the pump comes on. I think my wiring is correct, the diagram for relay is terminal 87 12v in, to this I have the mire from battery. Terminal 85 is geound, no brainer. Terminal 86 on/off switch, to this I put the wire from existing lift pump. Terminal 30/51 is 12 volt out, to this I put the wire to power the pusher pump.

Does this sound correct, and is the problem as I suspect and the Radio Shack relay is bad?

Larry

 

[Steve St.Laurent]

Nope, you've got it wired wrong. Pin 85 (or 86 depenidng on how you wire it) should be connected to the existing lift pump 12v source, pin 86 (or 85 - oppositie of the other) should be connected to ground. Pin 30 should be connected to the positive of your pusher pump, pin 87 should be connected to a 12v source (put a fuse there - I'd recommend a 20a fuse). How relays work is when 12v is applied to pin 85-86 then the switch is closed and current flows from pin 87 to pin 30. If there isn't 12v on 85-86 then current flows from pin 87a to 30. So you can choose to put current through to pin 30 either when there's 12v from 85-86 (feed is from 87 - normally open) - or when there's no 12v from 85-86 (feed is from 87a - normally closed). Hope that makes sense.



After reading over it again your close - but have the 87/87a-30 wires different than most would - if you just move the wire that you have on 87 to 87a you'll be fine. The way you have it wired 12v is applied to your pusher pump except when the engine mounted pump see's 12v. By moving the wire from 87 to 87a you'll only get 12v to the pusher pump when the engine mounted pump see's 12v. Normally your 12v in would be pin 30 - and then you'd select normally open (pin 87) or normally closed (pin 87a).

 

[Larry Willard]

Well got it runing, relay was bad, the pump ran even if the trigger wire was disconnected. Thanks Steve for the reply even though I was still confused after your reply. tmacc confirmed over the phone that the wiring was correct, he had the same relay on his truck.

Larry