How do I....?, I need to create a "switched" ciruit |
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How do I....?, I need to create a "switched" ciruit |
Carlitos Way |
Nov 26 2004, 02:16 PM
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#1
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I did it MY WAY Group: Members Posts: 1,337 Joined: 14-September 04 From: Simi Valley, CA Member No.: 2,757 Region Association: Southern California |
For some unknown reason, the PO had run the fuel pump off the Tail Light circuit, so I need to correct this. I tried other fuses in the fuse box, but they all seem to be either on all the time, or only on when specific things are turned on. So I decided to do things "better."
I would like to run a "switched" circuit to my fuse box, so I can have the fuel pump active only when the engine is running (ignition in the ON position?). I have upgraded to the 15 fuse box and would like to create two new switched fuse circuits for my fuel pump and my stereo (one each), that way I can get ahead of the game, and know exactly where everything is, rather than splicing more stuff and screwing around with the electrical system. Can you help/offer any suggestions? |
ws91420 |
Nov 26 2004, 04:04 PM
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#2
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Yes I have one a Lensley 914 Group: Members Posts: 2,063 Joined: 10-September 03 From: Ruther Glen,VA (halfway between sticks and civilization) Member No.: 1,137 Region Association: MidAtlantic Region |
Get a test light. Check fuses with key off for power. make note. Turn key on check circuits that didn't have power before. Any of those w/power after key on are switched circuits.
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TheCabinetmaker |
Nov 26 2004, 04:12 PM
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#3
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
There is already a dedicated circuit for the fuel pump on the relay board.
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Carlitos Way |
Nov 26 2004, 04:46 PM
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#4
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I did it MY WAY Group: Members Posts: 1,337 Joined: 14-September 04 From: Simi Valley, CA Member No.: 2,757 Region Association: Southern California |
QUOTE(vsg914 @ Nov 26 2004, 02:12 PM) There is already a dedicated circuit for the fuel pump on the relay board. So... where id the relay at? I'd really like to know... sorry, but the manuals aren't much help here. |
TheCabinetmaker |
Nov 26 2004, 05:10 PM
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#5
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
The power for the pump comes from the #13 pin on the 14 pin connector on the relay board. There are two fuses on the relay board. IIRC the rear one is for the fuel pump, and one of the black round relays also controls it. There are some other folks here who can splain it lots better than me. Can anyone help us out?
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hargray2 |
Nov 26 2004, 05:24 PM
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#6
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fuh-q Group: Members Posts: 302 Joined: 12-December 03 From: hardeeville,sc Member No.: 1,432 |
Here. Yes, the back fuse does include the fuel pump, so make sure it is there.
Attached thumbnail(s) |
Carlitos Way |
Nov 26 2004, 05:25 PM
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#7
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I did it MY WAY Group: Members Posts: 1,337 Joined: 14-September 04 From: Simi Valley, CA Member No.: 2,757 Region Association: Southern California |
Is that the realy board inside the engine compartment? which relay?
I've got it open right now... |
Carlitos Way |
Nov 26 2004, 05:29 PM
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#8
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I did it MY WAY Group: Members Posts: 1,337 Joined: 14-September 04 From: Simi Valley, CA Member No.: 2,757 Region Association: Southern California |
Wow, that's a great diagram, and I really appreciate the captions. So, can I run a "jumper cable" to a pump that has been relocated to the front? or am I just asking for trouble?
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ws91420 |
Nov 26 2004, 05:36 PM
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#9
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Yes I have one a Lensley 914 Group: Members Posts: 2,063 Joined: 10-September 03 From: Ruther Glen,VA (halfway between sticks and civilization) Member No.: 1,137 Region Association: MidAtlantic Region |
Yes you can jumper it. But you will be using the original wiring. Are you using FI or carbs? What year car?
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TheCabinetmaker |
Nov 26 2004, 05:39 PM
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#10
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Thanks Hargray. That's the ticket. BTW, where did you get that pic from?
If you only have three relay's, it's the one to the front. Four, it's the second from the front. |
Carlitos Way |
Nov 26 2004, 05:49 PM
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#11
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I did it MY WAY Group: Members Posts: 1,337 Joined: 14-September 04 From: Simi Valley, CA Member No.: 2,757 Region Association: Southern California |
thanks for your response...
To answer your question... I didn't jumper it... the PO had relocated it, but he dragged the wire connection from the brake fuse. So, every time I step on the brake the car dies. Still trying to figure out where to wire it from. I don't mind creating a dedicated circuit for it... I just wish I knew how. Otherwise.. can I run a jumper from the red/black wire to the fuel pump and have it only kick in with the ignition in the ON position? C. |
Joe Ricard |
Nov 26 2004, 06:05 PM
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#12
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Well here is a "no shit" what I did.
I got some black wire and had some leftover brown wire. Connected the wires back in the harness from the relay board. (stayed in the plastic wire housings). Routed them down through the rubber housing. (looks like a gooey duck). in the engine front shelf. Then routed on through the firewall and followed the rest of the cable run up to the footwell and then split off through a grometed hole and on to the pump. Drill new hole used new grommet from Lowes. I also marked the black wire with red stripe so I could tell it apart 20 years from now. PITA but I wasn't going to be a DAPO. |
hargray2 |
Nov 26 2004, 06:08 PM
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#13
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fuh-q Group: Members Posts: 302 Joined: 12-December 03 From: hardeeville,sc Member No.: 1,432 |
IIRC the fuel pump relay is the second position starting from the rear. You could go from the relay board all the way to the front. This would certainly be the easiest route. I'm not sure what the factory did when they relocated the pump on the later cars.
This is better than adding more wiring to your car. It WILL be a pain getting the wire through the boot at the firewall. |
TheCabinetmaker |
Nov 26 2004, 06:15 PM
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#14
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
QUOTE(hargray2 @ Nov 26 2004, 06:08 PM) IIRC the fuel pump relay is the second position starting from the rear. You could go from the relay board all the way to the front. This would certainly be the easiest route. I'm not sure what the factory did when they relocated the pump on the later cars. Hmm, I can pull the second or third and the pump still won't run. 75 model. |
hargray2 |
Nov 26 2004, 06:32 PM
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#15
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fuh-q Group: Members Posts: 302 Joined: 12-December 03 From: hardeeville,sc Member No.: 1,432 |
QUOTE(vsg914 @ Nov 26 2004, 04:15 PM) Hmm, I can pull the second or third and the pump still won't run. 75 model. Correct. There are 4 relay positions. The first one (starting from the front) is usually empty. That's the rear window defroster option. The second from the front is the "power supply" relay. It gives power to the fuel pump relay (not the fuel pump) and I think the FI too. The third relay from the front is the pump relay. This relay gets switched on from the second relay. This relay actually gives the fuel pump its power and also powers more FI stuff. The last relay is the heater blower relay. Relay 3 is required for the fuel pump to run. Relay 2 is required for relay 3 to run. So actually relay 2 is the fuel pump relay's relay (IMG:style_emoticons/default/biggrin.gif). Both 2 and 3 are needed to run the fuel pump. I guess they did this so the pump wouldn't run if the other circuit failed to power up the FI properly. BTW-relay 3 (from the front) is the second from the back. I went from the back so he wouldn't count the empty socket on position 1 (rear window defrost). |
TheCabinetmaker |
Nov 26 2004, 06:38 PM
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#16
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Thanks Daniel. Believe it or not, that does make sense. I did know the 3rd controled the FI, but was not aware it was powered by #2
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DNHunt |
Nov 26 2004, 06:54 PM
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#17
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914 Wizard? No way. I got too much to learn. Group: Members Posts: 4,099 Joined: 21-April 03 From: Gig Harbor, WA Member No.: 598 |
How the hell does a guy from Mississippi know about geoducks (gooey ducks)? Awful good eating but, hard to dig
Dave Attached image(s) |
hargray2 |
Nov 26 2004, 07:13 PM
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#18
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fuh-q Group: Members Posts: 302 Joined: 12-December 03 From: hardeeville,sc Member No.: 1,432 |
I've heard rocky mountain oysters are hard to catch and harvest. (IMG:style_emoticons/default/confused24.gif)
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ws91420 |
Nov 26 2004, 07:18 PM
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#19
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Yes I have one a Lensley 914 Group: Members Posts: 2,063 Joined: 10-September 03 From: Ruther Glen,VA (halfway between sticks and civilization) Member No.: 1,137 Region Association: MidAtlantic Region |
You can jumper the third relay to activate the pump with the stock wiring and with key on. I can't remember right now which pins right now, but this is how I powered my fuel pump when converting to carbs. This is only true on 75 and 76 models which had the pump up front from factory. Otherwise you have to wire it yourself (IMG:style_emoticons/default/biggrin.gif)
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94teener |
Nov 26 2004, 08:20 PM
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#20
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Member Group: Members Posts: 209 Joined: 6-February 04 From: Jacksonville, FL Member No.: 1,636 |
All you have to do is make sure you have the aft 3 relays in the relay board in the engine compartment. Then, wire one wire from pin IV of the
four pin connector as shown by the black wire in the attached pic. That's it, you've got fuel pump power with the ignition switch on. Phil Attached image(s) |
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