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> fuel pump wiring, electical novice!
malcolm2
post Feb 4 2013, 08:10 PM
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I admit that I am out of my league when it comes to electical wiring, theory, and reading diagrams, so I have a question....

I am going thru the wiring on my 75 L-jet. I replaced the OEM fuse box and just kinda kept going. I towed this car home 18 months ago, so I have no idea what works and what does not.

Anyway, I see a heavier gauge wire in the gas tank area (tank is out). The wire is Black with a Red stripe. I followed it back to the relay board and figured it has something to do with the fuel pump. The color diagram on PP leads me to the FP relay and then on to a white wire labeled 12.
Attached Image

The PO has the fuel pump wired directly to the coil with a heavy red wire that I know was not OEM. And this mystery BLK/RED wire is cut on the Fuel Pump end. Any ideas why the PO did this? Will I need a new relay, maybe?

Thoughts anyone?

Thanks, Clark
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Spoke
post Feb 4 2013, 09:14 PM
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Where is the fuel pump located now? Under the gas tank or in the engine compartment?

The wire you successfully traced back to the relay board is for the fuel pump when it is located under the gas tank. The positive terminal of the fuel pump goes to the black/red wire. the negative terminal of the fuel pump goes to chassis ground.
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timothy_nd28
post Feb 4 2013, 09:17 PM
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I'm guessing that he aborted the Ljet FI system, and installed a carb low pressure fuel pump. The dual relay thats mounted near the ECU brain, controls the fuel pump.
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malcolm2
post Feb 4 2013, 10:43 PM
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This wire had been cut. it had no connector. Car is a 75 1.8 with L-jet and the pump is under the tank. All the FI stuff was installed when I got the car, so no evidence of carbs. Not sure about the DUAL RELAY tho. I don't see that mentioned in the Haynes book either.
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timothy_nd28
post Feb 5 2013, 01:01 AM
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Dual relay looks like this
Attached Image
Attached Image

Pin 88d feeds power to your fuel pump
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timothy_nd28
post Feb 5 2013, 01:11 AM
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or the dual relay could look like this, different styles exist.
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malcolm2
post Feb 5 2013, 01:40 PM
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QUOTE(timothy_nd28 @ Feb 5 2013, 01:01 AM) *

Dual relay looks like this
Attached Image
Attached Image

Pin 88d feeds power to your fuel pump


Wait a minute....I think it is either currently connected to the FI harness or still in the bag when it came back from Bowlsby. I'll dig around and find it, then probably have more questions.

Now I'm getting somewhere. I hope.... (IMG:style_emoticons/default/unsure.gif)
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timothy_nd28
post Feb 5 2013, 02:27 PM
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If you can, post some pictures of your setup
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Dave_Darling
post Feb 5 2013, 03:08 PM
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The dual relay should be hanging off the battery tray.

--DD
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L73
post Feb 5 2013, 04:17 PM
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ahhh the L-Jet (IMG:style_emoticons/default/headbang.gif) I ran the L-jet for five years on my 75 1.8 before i gave up and went to the Dellorto 36s... How is you Air Flow Meter ?? That is the heart and soul of the L Jet... Big silver thing driver side in the engine bay... Open the black lid and you will see a needle...with the key on ...if you move that needle your fuel pump should start pumping if the wires are hooked up right....
I have a bunch of parts if you need them.....
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malcolm2
post Feb 5 2013, 09:10 PM
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QUOTE(L73 @ Feb 5 2013, 04:17 PM) *

ahhh the L-Jet (IMG:style_emoticons/default/headbang.gif) I ran the L-jet for five years on my 75 1.8 before i gave up and went to the Dellorto 36s... How is you Air Flow Meter ?? That is the heart and soul of the L Jet... Big silver thing driver side in the engine bay... Open the black lid and you will see a needle...with the key on ...if you move that needle your fuel pump should start pumping if the wires are hooked up right....
I have a bunch of parts if you need them.....


car is totally stripped down. I rebuilt the engine about a year ago and i have been cleaning up rust since it was done. I am now putting stuff back together and finding other stuff that doesn't look right or had been disconnected by the PO.

Thanks for the tip, maybe I can dry fit everything together and test it.
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malcolm2
post Feb 5 2013, 09:11 PM
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QUOTE(Dave_Darling @ Feb 5 2013, 03:08 PM) *

The dual relay should be hanging off the battery tray.

--DD


I do remember that now. I guess that is what the zip tie is for. I found the relay in Bowlsby's bag.
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malcolm2
post Feb 5 2013, 09:17 PM
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QUOTE(timothy_nd28 @ Feb 5 2013, 02:27 PM) *

If you can, post some pictures of your setup


No engine yet, just now getting the wires back into each trunk. (IMG:style_emoticons/default/welder.gif) Done welding and beginning to assemble. Trying to find all the parts I took off 18 months ago.
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