Got the supplemental vacuum pump today. It requires power from the + Bat side(I'm going to use the horn relay bus bar, is this right? or possibly the jct block) + from ignition(short of taking it back to the ignition terminal on the fuse block is there a igintion source in the engine compartment?) and of course a - ground.

Should a relay be used on both the + Bat and + ignition wires? If so how do I wire them. i have two 30amp 5 pole relays(was hoping to use for electric fans but see during my research that larger relay's are recommended, up to 70amp) if relays are recommened where do I put them, close to the power source(bat, horn relay, jct block or close to the power consuming unit(vacuum pump or fans)


TIA Pete

Yes use a relay, the best source for power is the horn relay. Wire the relay as follows. Power from the horn relay, be sure to use a fusible link, a circuit breaker or an inline fuse, connects to #30 of the relay. I would use 12 ga wire with 16 ga fusible link. Relay #87 connects to the vacuum pump + also use 12 ga wire. Relay #85 gets grounded, 18 ga wire. Relay #86 is switched power to operate the relay, 18 ga wire.

Mount the relay wherever it is convenient close to the horn relay or close to the vacuum pump makes no difference. The fuse, fusible link or circuit breaker should be as close to the horn relay as possible.

Yes use a relay, the best source for power is the horn relay. Wire the relay as follows. Power from the horn relay, be sure to use a fusible link, a circuit breaker or an inline fuse, connects to #30 of the relay. I would use 12 ga wire with 16 ga fusible link. Relay #87 connects to the vacuum pump + also use 12 ga wire. Relay #85 gets grounded, 18 ga wire.

I understand the above but below I'm confused. See how electrically challenged I am.


Relay #86 is switched power to operate the relay, 18 ga wire. So are you saying to hook #86 to ignition power? ie something like the yellow wire at the wiper motor? Wouldn't that be supplying the relay with two different sources of power?

Mount the relay wherever it is convenient close to the horn relay or close to the vacuum pump makes no difference. The fuse, fusible link or circuit breaker should be as close to the horn relay as possible.

The motor has three wires red(+ Bat #87) Pink(+ignition) and black(-ground most likely firewall) or are you saying to connect the pink wire to #86.

The motor has its own internal switch(does that mean connect #86 and #87 to the same power source? Jumpered together?) that turns on at HG below 5 and off at 20 I believe. I thought I needed to use two relays, one for the +Bat(red wire) and the other for the + ignition wire(pink).

I apologize for my ignorance and appreciate your patience.

TIA Pete

Pete,

Part of what you need to know about your vacuum pump is how much current it draws at startup and also during operation. With the wiring setup and internal switching you have you probably do not need a relay at all. Effectively you have a relay internal to the pump. So you just need to wire up the main supply with appropriate sized wire and circuit protection (fuse/breaker/link).

Steve

Pete,

Part of what you need to know about your vacuum pump is how much current it draws at startup and also during operation. With the wiring setup and internal switching you have you probably do not need a relay at all. Effectively you have a relay internal to the pump. So you just need to wire up the main supply with appropriate sized wire and circuit protection (fuse/breaker/link).

Steve
Correct. As a test, just fuse the + from ignition terminal with a small fuse like a 3amp, if it doesn't blow that side if the circuit doesn't need much power.

The more I think about it your probably right. Not sure how to find the amperage draw out. I think I'll run 10ga from the bus bar to the red wire power wire of the pump and put an inline 30 amp circuit breaker in it, then connect the pink ignition wire of the pump to the yellow wiper motor wire and the black ground wire of the pump to the fire wall. Man this wiriing and electrical stuff is challenging!! Thought's, ideas? Thanks Pete

This might help:

http://www.chevelles.com/forums/showthread.php?t=107812

Pictures & everything!

The more I think about it your probably right. Not sure how to find the amperage draw out. I think I'll run 10ga from the bus bar to the red wire power wire of the pump and put an inline 30 amp circuit breaker in it, then connect the pink ignition wire of the pump to the yellow wiper motor wire and the black ground wire of the pump to the fire wall. Man this wiriing and electrical stuff is challenging!! Thought's, ideas? Thanks Pete
Since you have wire coming out of the pump... what size are the current wires? That should give you an idea of what kind of wires and currents to plan for.

Otherwise sounds like you are on track.

One point worth mentioning is in regards to terminals and connections. Since this is somewhat of a critical system you do not want it to fail. So I would recommend adding solder to any terminal crimp connections. This will keep crud out and provide mechanical support for improved reliability.

Steve

Steve the wires appear to be 14-16 gauge coming out of the pump. Pete

Pete,

So err one size to the larger and run 14 gauge wiring with (I am guessing here) a 20 amp fuse and you should be good to go. Note that there really is very little downside to using wire that is larger than required and sometimes (like for a long length run) it is actually a good idea.

That is if you have not already done it since I last checked/posted to this thread ;-)

Steve

Thanks to all for your responses and help.Steve no I haven't done this yet. It is our hope to finish this wiring "upgrade" this weekend. Spent this week asking questions, reading and locating the needed materials. Thanks Pete

Found some more info on this pump and it's suggested that a ten amp relay and fuse be used. I assume then that the 'draw" isn't to much. TIA Pete

Nope, 10 amps is not too much. Not trivial either. Enough for a dedicated circuit using the typical 16 gauge wire.

Steve