Fuel Pump Harness Routing – Need Help Tracing the Path to the Trunk (CSi Restoration)

[LEO]

Well, as I’ve mentioned before, I’m trying to bring my White Shark CSi back to life — it’s been completely disassembled since 2019. Right now, we’re knee-deep in the restoration of the wiring harness, and I’ve run into something strange.

I found a section of the harness with very long, burned wires that belong to the fuel pump circuit. Oddly enough, all of these wires are yellow, but according to the documentation I’ve managed to find, they should be green with a white stripe, and of course brown for ground. We’ve already corrected that part, but now we’re breaking our heads trying to figure out how to route this harness properly.

We know the fuel pump relay sits under the seat, and that the power to the relay comes from a male connector under the rear “turtle” panel, but I’m not sure how it gets to the trunk — or through which hole it passes.

If anyone has photos or diagrams to help me visualize this, I’d be deeply grateful from the bottom of my heart.

Cheers,

 

[ScottAndrews]

I can't help with the routing because I have a different car (CS) , but I am wondering about your splices. First off can you be certain that you got the brown wire on the grounded yellow wire? Second, how did you make the electrical connection? Solder connections out in the wild may crack from temperature variation and vibration. generally splices are done using crimp connectors, or just spade connectors if it is one wire. Third, it looks like you just wrapped the splices with black electrical tape. That stuff will dry out and unravel at the splice over time. I'd at a minimum replace the tape with a heat shrink sleeve (will need to cut and re-joint the wires to do this.

While it s not a perfect solution, I have used Ancor marine crimp splices in my boat with good success (in a very damp environment). These come with a heat shrink sleeve over the joint. So you insert the wires, crimp and then heat the sleeve. The heat shrinks the sleeve and also activates a sealing goo that melts around the wires. So the result is pretty much water and vibration proof. See pic below.

There are also soldered splices that operate onthe same principle (with solder instead of a crimp). In those the het from the heat gun melts the older and also shrinks the tube and activates the goo. Pic below.

 

[LEO]

I can't help with the routing because I have a different car (CS) , but I am wondering about your splices. First off can you be certain that you got the brown wire on the grounded yellow wire? Second, how did you make the electrical connection? Solder connections out in the wild may crack from temperature variation and vibration. generally splices are done using crimp connectors, or just spade connectors if it is one wire. Third, it looks like you just wrapped the splices with black electrical tape. That stuff will dry out and unravel at the splice over time. I'd at a minimum replace the tape with a heat shrink sleeve (will need to cut and re-joint the wires to do this.

While it s not a perfect solution, I have used Ancor marine crimp splices in my boat with good success (in a very damp environment). These come with a heat shrink sleeve over the joint. So you insert the wires, crimp and then heat the sleeve. The heat shrinks the sleeve and also activates a sealing goo that melts around the wires. So the result is pretty much water and vibration proof. See pic below.

There are also soldered splices that operate onthe same principle (with solder instead of a crimp). In those the het from the heat gun melts the older and also shrinks the tube and activates the goo. Pic below.

Hi Scott — thanks for your reply.





What you mentioned (tape splices, add-ons, etc.) is exactly the mess I found in the car — the fuel pump harness was a total disaster. We only used it to take cable measurements; we’ve built the harness from scratch.


Honestly, it looked like a crime scene — the CSI harness before we got to it.





Thanks again for the advice, any ideas to make it cleaner or safer are always welcome.

 

[ScottAndrews]

Hi Scott — thanks for your reply.

What you mentioned (tape splices, add-ons, etc.) is exactly the mess I found in the car — the fuel pump harness was a total disaster. We only used it to take cable measurements; we’ve built the harness from scratch.

Honestly, it looked like a crime scene — the CSI harness before we got to it.

Thanks again for the advice, any ideas to make it cleaner or safer are always welcome.

I assume the lower harness inthe pic is the new one. What did you use for the sheath? And how did you make the numbered yellow collar?

 

[LEO]

I assume the lower harness inthe pic is the new one. What did you use for the sheath? And how did you make the numbered yellow collar?

Yes, the lower harness in the picture is the new one.
For the sheath, I used Alpha Wire PVC Sleeve Tube Tubing (non-shrink).
I didn’t use yellow wires — according to the wiring diagrams, I replaced the yellow ones with green/white wires, and the brown wire will be the ground.
I haven’t numbered the green/white wires yet, so I’m not sure if that’s what you were referring to.
Do you think I should label or number anything in particular?
Thanks for your interest!

 

[CharlesJ]

At the risk of giving you misinformation (I have a CS), I believe all the wiring that goes into the trunk follows the same path together: Through the driver side outside floor pass through to the rear seat cavity, up along the top edge of the inside wheel well arch, and through a hole where the interior wheel well top meets the trunk. This is the same path the rear lights, fuel level sender, etc travel. I cannot verify this is true for the original CSI fuel pump power specifically, but that is how everything else routes, and there is an outlet hole for the wires from inside the trunk to the fuel pump mount area. This is how I routed my electric fuel pump conversion for my CS.

 

[ScottAndrews]

Yes, the lower harness in the picture is the new one.
For the sheath, I used Alpha Wire PVC Sleeve Tube Tubing (non-shrink).
I didn’t use yellow wires — according to the wiring diagrams, I replaced the yellow ones with green/white wires, and the brown wire will be the ground.
I haven’t numbered the green/white wires yet, so I’m not sure if that’s what you were referring to.
Do you think I should label or number anything in particular?
Thanks for your interest!

I was referring to the yellow collar on the sheath circled in the image below. Those usually have a part number or something. I'm on the fence re numbering each wire. it is helpful for future troubleshooting, but the connector and the color code in conjunction with the wiring diagram define each wire without any number.

 

[ScottAndrews]

At the risk of giving you misinformation (I have a CS), I believe all the wiring that goes into the trunk follows the same path together: Through the driver side outside floor pass through to the rear seat cavity, up along the top edge of the inside wheel well arch, and through a hole where the interior wheel well top meets the trunk. This is the same path the rear lights, fuel level sender, etc travel. I cannot verify this is true for the original CSI fuel pump power specifically, but that is how everything else routes, and there is an outlet hole for the wires from inside the trunk to the fuel pump mount area. This is how I routed my electric fuel pump conversion for my CS.

I agree. I can't imagine that there is any significant difference between CS and CSI fuel pump wiring.

 

[stphers]

As far as labeling goes, a buddy of mine used to print out on paper with an adhesive backing, small little descriptions that he would attach to the wire and then put clear heat shrink tubing over it Very time consuming but looked cool and was real easy to put things back together when you had to take things apart

The black PVC tubing is available at McMastersCarr and there was a fellow on the 2002FAQ that selling twocolor wire specific to BMW's

Thanks, Rick

 

[Christopher]

The wiring passes through one of the rubbers grommets in the boot floor to the pump. I'm away travelling at the moment so don't have an image of my own to send but have pinched this one (courtesy of BarryG) from the site which shows how it should sit. It might appear a little untidy but is covered by the rear boot board. This is how it was done from factory.

 

[LEO]

The wiring passes through one of the rubbers grommets in the boot floor to the pump. I'm away travelling at the moment so don't have an image of my own to send but have pinched this one (courtesy of BarryG) from the site which shows how it should sit. It might appear a little untidy but is covered by the rear boot board. This is how it was done from factory.

Friend, thank you for sharing this image — now the cable length makes perfect sense, as well as the routing that goes in the opposite direction of the other harness. This really helps clarify how the setup is supposed to look.

 

[LEO]

I was referring to the yellow collar on the sheath circled in the image below. Those usually have a part number or something. I'm on the fence re numbering each wire. it is helpful for future troubleshooting, but the connector and the color code in conjunction with the wiring diagram define each wire without any number.

View attachment 210712

Sorry for not understanding you earlier. That yellow collar is from the original harness — it even has a part number, but when I looked it up on Google, nothing came up. I decided to keep it anyway, since it was already detached from the original harness.