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This look right? (relay question)

Posted By: Mr.Yuck

This look right? (relay question) - 03/20/11 02:00 AM

Hooked up my fuel pump and was wondering if this looks ok or do I have something wrong... Relay is back by the pump, switch is in console and (+) is going to come from the Key on or Run position.

Attached picture 6538884-switch.jpg
Posted By: RapidRobert

Re: This look right? (relay question) - 03/20/11 03:10 AM

You're running switched 12V (ign1) to the pump but it goes thru a relay right b 4 the pump. What is the relay connecting???
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 03:13 AM

Quote:

You're running switched 12V (ign1) to the pump but it goes thru a relay right b 4 the pump. What is the relay connecting???



the pump? Does the relay need to go b4 the swtich?
Posted By: Mopar_Country

Re: This look right? (relay question) - 03/20/11 03:25 AM

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/20/11 03:36 AM

A relay is used so the switched power is a very minimal load (the relay draw-in coil) but a second power lead typically straight from the battery or the starter relay so it's a high amp full voltage direct source actually provides the power to run the main load (fuel pump).. Your circuit does have a main power lead...
Posted By: Jim_Lusk

Re: This look right? (relay question) - 03/20/11 04:20 AM

Yep, add a high current 12v feed to the switched high current side of the relay.
Posted By: DirectSubjection

Re: This look right? (relay question) - 03/20/11 08:27 AM

As mentioned above - relays should have 4 connections - ground, major positive power from a direct battery source, minor positive activation power from a switched source (to turn it on), and a major power out feed to the related device.
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/20/11 08:33 AM

Quote:

As mentioned above - relays should have 4 connections - ground, major positive power from a direct battery source, minor positive activation power from a switched source (to turn it on), and a major power out feed to the related device.



Another way it can be wired is to switch one relay control leg to ground & jump the battery power to the other relay control leg...

But to the O/P pay no attention to this as it only complicates things..
Posted By: Rockland71GTX

Re: This look right? (relay question) - 03/20/11 08:44 AM

Here is a quick drawing showing how the circuit should look. I put the indicator lamp on the fuel pump leg so you have a light when there is power to the pump versus power to the relay (will show if relay fails for troubleshooting)

Attached picture 6539426-fuelpumprelay.JPG
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 02:33 PM

Quote:

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf



thanks, that's it. I could remember. last I did one the battery was in the trunk. I'll switch it up. Hope to get it fired up today.

the 85 post can that go to the switch or should it run to the key on then the switch?
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/20/11 05:38 PM

Quote:

Quote:

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf



thanks, that's it. I could remember. last I did one the battery was in the trunk. I'll switch it up. Hope to get it fired up today.

the 85 post can that go to the switch or should it run to the key on then the switch?



Do you want to run the pump with the engine off? You can wire it either way but since the only reason to run it is when the engine is running it makes sense to feed it from a key on power source..
Posted By: Yancy Derringer

Re: This look right? (relay question) - 03/20/11 06:14 PM

Quote:

Quote:

Quote:

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf



thanks, that's it. I could remember. last I did one the battery was in the trunk. I'll switch it up. Hope to get it fired up today.

the 85 post can that go to the switch or should it run to the key on then the switch?



Do you want to run the pump with the engine off? You can wire it either way but since the only reason to run it is when the engine is running it makes sense to feed it from a key on power source..



To add to the above, unless your battery is in the trunk, and that's where you pulled power, there is no good reason to mount the relay in the back. You just have to run the switch lead further.

As someone else said, I would at least run the switch lead TO IGNITION RUN so that the pump is on/ off with the key.

ALSO consider doing one of two things: either find a "crash switch" and wire into the switch lead, or buy an oil pressure switch for the purpose.

That way if you wreck the car, the pump will not be operating.

Also, DID YOU FUSE it? Find out from the pump instructions what the pump draws in amps, and use the next size larger fuse. The fuse/ breaker should be as CLOSE TO THE BATTERY as possible.

WHAT SIZE WIRE are you running to the pump? Once again, find out what the pump draws. I would not use anything smaller than #12, and depending on the pump, possibly larger.
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 07:00 PM

Quote:

Quote:

Quote:

Quote:

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf



thanks, that's it. I could remember. last I did one the battery was in the trunk. I'll switch it up. Hope to get it fired up today.

the 85 post can that go to the switch or should it run to the key on then the switch?



Do you want to run the pump with the engine off? You can wire it either way but since the only reason to run it is when the engine is running it makes sense to feed it from a key on power source..



To add to the above, unless your battery is in the trunk, and that's where you pulled power, there is no good reason to mount the relay in the back. You just have to run the switch lead further.

As someone else said, I would at least run the switch lead TO IGNITION RUN so that the pump is on/ off with the key.

ALSO consider doing one of two things: either find a "crash switch" and wire into the switch lead, or buy an oil pressure switch for the purpose.

That way if you wreck the car, the pump will not be operating.

Also, DID YOU FUSE it? Find out from the pump instructions what the pump draws in amps, and use the next size larger fuse. The fuse/ breaker should be as CLOSE TO THE BATTERY as possible.

WHAT SIZE WIRE are you running to the pump? Once again, find out what the pump draws. I would not use anything smaller than #12, and depending on the pump, possibly larger.



have #12 was going to run it from the "run" so it's only on when key is on, I also have a switch so the key has to be on and the switch up. Holley blue pump. I have 15amp fuse now but can swap it w/o issue. Should I run both main feed and switch from "run" or only switch and main from 12v side of the starter relay?
didn't really see the need to go all the way to the battery.
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/20/11 07:20 PM

The whole purpose of a relay is to supply full clean power to the load... The main feed should go to either the battery, the battery post on the starter relay or the battery post on the starter.... You don't want the actually supply lead switched but you do want it fused close to where it gets power....
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 07:24 PM

thanks...will do.
Posted By: Yancy Derringer

Re: This look right? (relay question) - 03/20/11 08:16 PM

Quote:

Quote:

Quote:

Quote:

Quote:

This might help.

http://www.pacificp.com/pdf/Fuel%20Pump%20Relay%20Unit%20%28Online%29%20Diagram.pdf



thanks, that's it. I could remember. last I did one the battery was in the trunk. I'll switch it up. Hope to get it fired up today.

the 85 post can that go to the switch or should it run to the key on then the switch?



Do you want to run the pump with the engine off? You can wire it either way but since the only reason to run it is when the engine is running it makes sense to feed it from a key on power source..



To add to the above, unless your battery is in the trunk, and that's where you pulled power, there is no good reason to mount the relay in the back. You just have to run the switch lead further.

As someone else said, I would at least run the switch lead TO IGNITION RUN so that the pump is on/ off with the key.

ALSO consider doing one of two things: either find a "crash switch" and wire into the switch lead, or buy an oil pressure switch for the purpose.

That way if you wreck the car, the pump will not be operating.

Also, DID YOU FUSE it? Find out from the pump instructions what the pump draws in amps, and use the next size larger fuse. The fuse/ breaker should be as CLOSE TO THE BATTERY as possible.

WHAT SIZE WIRE are you running to the pump? Once again, find out what the pump draws. I would not use anything smaller than #12, and depending on the pump, possibly larger.



have #12 was going to run it from the "run" so it's only on when key is on, I also have a switch so the key has to be on and the switch up. Holley blue pump. I have 15amp fuse now but can swap it w/o issue. Should I run both main feed and switch from "run" or only switch and main from 12v side of the starter relay?
didn't really see the need to go all the way to the battery.




I looked up the Holley blue and it claims to only draw 3A and 7 1/2 A fuse is what they recommend. Frankly, I was surprised it was so low.

No 12 main feed should be fine in that case Starter relay should be OK, just put a fuse as close to that as you can.
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 08:33 PM

WOW 7.5 i thought 10 least.... guess i'll run to the exxon
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/20/11 09:36 PM

Ok so it works whe i have the switch and main into the hot side of the relay. However when i hook the switch into the brown relay it's a no-go. I thought that wire was "hot" when the key was on? Do I have to run the switch lead into the fuse box?
Posted By: Yancy Derringer

Re: This look right? (relay question) - 03/20/11 10:13 PM

Quote:

Ok so it works whe i have the switch and main into the hot side of the relay. However when i hook the switch into the brown relay it's a no-go. I thought that wire was "hot" when the key was on? Do I have to run the switch lead into the fuse box?



Now I'm confused. You need to post what sort of relay you are using so we can help get the contact layout figured.

The relay should have at least two contacts.

The pump hooks to one contact

The big hot feed goes to the other

The relay should have two coil terminals

One gets grounded

The other goes to your small wire going to the switched power

To check your relay, unhook the pump lead and turn the key / switch on/ off. You should hear the relay click, might need a friend.

Or turn on key, pull switched lead off relay, it should drop out, hook it up, click in. Turn off key/ switch, recheck. Relay, of course should NOT click.

If you go to the Holley site, there is a LOT of info there:

http://www.holley.com/12-802-1.asp

READ THIS:

http://www.holley.com/data/Products/Technical/199R7914-3rev2.pdf

and some more good general info

http://www.holley.com/data/Products/Technical/Fuel%20Pump%20Tech%20Info.pdf
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/21/11 12:11 PM

Quote:

Quote:

Ok so it works whe i have the switch and main into the hot side of the relay. However when i hook the switch into the brown relay it's a no-go. I thought that wire was "hot" when the key was on? Do I have to run the switch lead into the fuse box?



Now I'm confused. You need to post what sort of relay you are using so we can help get the contact layout figured.

The relay should have at least two contacts.

The pump hooks to one contact

The big hot feed goes to the other

The relay should have two coil terminals

One gets grounded

The other goes to your small wire going to the switched power

To check your relay, unhook the pump lead and turn the key / switch on/ off. You should hear the relay click, might need a friend.

Or turn on key, pull switched lead off relay, it should drop out, hook it up, click in. Turn off key/ switch, recheck. Relay, of course should NOT click.

If you go to the Holley site, there is a LOT of info there:

http://www.holley.com/12-802-1.asp

READ THIS:

http://www.holley.com/data/Products/Technical/199R7914-3rev2.pdf

and some more good general info

http://www.holley.com/data/Products/Technical/Fuel%20Pump%20Tech%20Info.pdf



standard 4 prong... I think the posts are 85, 86, 87 and 30. Have it all wired correctly as per insructions on package.
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/21/11 04:16 PM

I would most likely hook terminal 86 up to the ballast resistor

terminal 30 is hooked to battery power (starter relay)
85 goes to ground
87 goes to your pump

It sounds like for what ever reason your chosen switched power source isn't getting power.... Reason I'd use the ballast is you don't want power in accessory position like most stuff under the dash... & the relay draws so little power it won't effect anything.... I you want to have a over-ride switch to shut the pump down hook it up to terminal 85 so the ground is eliminated.. If you decide to add a inertia (crash) switch it also would go in the terminal 85 lead...
Posted By: Mr.Yuck

Re: This look right? (relay question) - 03/21/11 04:25 PM

Quote:

I would most likely hook terminal 86 up to the ballast resistor

terminal 30 is hooked to battery power (starter relay)
85 goes to ground
87 goes to your pump

It sounds like for what ever reason your chosen switched power source isn't getting power.... Reason I'd use the ballast is you don't want power in accessory position like most stuff under the dash... & the relay draws so little power it won't effect anything.... I you want to have a over-ride switch to shut the pump down hook it up to terminal 85 so the ground is eliminated.. If you decide to add a inertia (crash) switch it also would go in the terminal 85 lead...



Never thought of using the ballast. either side work? I think the Schematic had 30 going to the pump, 85 was ground, and 86/87 was to power and switch, can't remember which was which.
Posted By: Boosted

Re: This look right? (relay question) - 03/21/11 05:02 PM

I run a constant voltage soleniod on my car. There is no need for a relay then. The constant voltage soleniod will only need 9v to activate it. Yhe pump will get full power then. Just a thought..

I run both of my pumps off the constant voltage soleniod.

And no it is not a ford soleniod.. They are not intended for constant power.
Posted By: 1_WILD_RT

Re: This look right? (relay question) - 03/21/11 05:19 PM

Quote:

I run a constant voltage soleniod on my car. There is no need for a relay then. The constant voltage soleniod will only need 9v to activate it. Yhe pump will get full power then. Just a thought..

I run both of my pumps off the constant voltage soleniod.

And no it is not a ford soleniod.. They are not intended for constant power.




What exactly do you think that style solenoid is?


It's a relay with the ground circuit internally grounded...



As far as powering the trigger of the relay off the ballast, either would work but I'd use the battery side...
Posted By: jbc426

Re: This look right? (relay question) - 03/21/11 07:13 PM

This helps me when using relays.

http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

I used dual 40 amp relays on my pump as recommended by Product Engineering as their pump draws some heavy current.


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