Electronics ?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Electronics ?
I have a electric water pump on my 454. I would like to build a relay or something with about a 5 second delay before the pump is "energized" -from the time I turn the key on to the time the pump comes on (don't want it taking amps while the engine is cranking). What would I need to build something like that?
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
A 555 timer chip will do it with very little componants. Just do a search on 555 timers.
You could also hook it up to an oil pressure switch. It might turn on during cranking if your engine is a bit slow to start.
Once oil pressure is present the water pump is powered. It might give you the delay you want without much building stuff.
You could also hook it up to an oil pressure switch. It might turn on during cranking if your engine is a bit slow to start.
Once oil pressure is present the water pump is powered. It might give you the delay you want without much building stuff.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Just use a relay. Use a ground and the starter signal for the switch side. Ignition power to the other side and then to the pump. Hook it up normally closed. Power to the pump when ignition is on, but not cranking.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Sounds like a workable approach - no power to the relay with key in crank position (as I understand it). Are these the normal relays that are used with fog lights or high power horns?
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
On a normal "Bosch" relay like driving lights or whatever you have 5 terminals. If you look on the side there is a diagram. 2 terminals correspond to a squiggly thing. That is the switch circuit. Put ground to one side and cranking voltage on the other, might use the yellow wire from the starter if your car was originally points. The other 3 terminals correspond to supply and normally open and normally closed. Hook ignition switched power to the supply post and power to the pump to the normally closed port (the one the line in the diagram is laying on). If you have ignition power and are not cranking, you will power the pump. While cranking, the relay will energize and take away power from the pump.
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