86' 740 fuel sender wiring Topic is solved

waynegarbo · Post by **waynegarbo** » 09 Dec 2018, 10:04

On my sending unit plug I have three wires, lavender, light grey, and Brown, yet, from the harness connector, I only have the lavender and grey wires. Now I'm putting in a sending unit out of an 87'. It's connector on the harness uses the 3rd, brown wire. Why is this so? What is the brown wire for.

lummert · Post by **lummert** » 09 Dec 2018, 12:06

The brown wire should be the gauge ground on later models. Earlier models probably connected to a different grounding terminal.

waynegarbo · Post by **waynegarbo** » 10 Dec 2018, 10:36

Since this latter model ground is wired into my car and I'm installing this sender with that ground, then I'm going to have to wire it in and connect it.

waynegarbo · Post by **waynegarbo** » 10 Dec 2018, 16:03

lummert wrote: ↑09 Dec 2018, 12:06 The brown wire should be the gauge ground on later models. Earlier models probably connected to a different grounding terminal.

Lummert the lavender wire powers the fuel pump, the grey is for the sender guage, and the brown must be the ground, because the 87' does have an added ground, unlike my 86'

lummert · Post by **lummert** » 11 Dec 2018, 09:32

Thinking the power wire to the fuel pump is labeled as pink on the wiring diagram. Wiring diagrams for the model year car you have are scarce. Volvo Green Book wiring diagrams are all that I could find.

stabworthy · Post by **stabworthy** » 31 Mar 2019, 16:28

waynegarbo wrote: ↑09 Dec 2018, 10:04 On my sending unit plug I have three wires, lavender, light grey, and Brown, yet, from the harness connector, I only have the lavender and grey wires. Now I'm putting in a sending unit out of an 87'. It's connector on the harness uses the 3rd, brown wire. Why is this so? What is the brown wire for.

waynegarbo, can i ask where you found the fuel sending unit for an '87? Did you pick this up from a junkyard and if so, does it look the same or just similar? I've been trying to find one new or used and haven't had any luck.

93Regina · Post by **93Regina** » 31 Mar 2019, 22:37

This is via dealer in Phoenix: Check fitment: Volvo 1389128, Fuel Tank Sending Unit

Expand the diagrams here

There were several versions of this part. If serious, I would contact them first, with your VIN: https://www.volvopartsofphoenix.com

waynegarbo · Post by **waynegarbo** » 03 Apr 2019, 16:23

stabworthy wrote: ↑31 Mar 2019, 16:28
waynegarbo wrote: ↑09 Dec 2018, 10:04 On my sending unit plug I have three wires, lavender, light grey, and Brown, yet, from the harness connector, I only have the lavender and grey wires. Now I'm putting in a sending unit out of an 87'. It's connector on the harness uses the 3rd, brown wire. Why is this so? What is the brown wire for.
waynegarbo, can i ask where you found the fuel sending unit for an '87? Did you pick this up from a junkyard and if so, does it look the same or just similar? I've been trying to find one new or used and haven't had any luck.

Stabworthy I got my sender out of the wrecking yard and yes it is the same. Look for the sender out of an 86' and 87'....an 85' didn't match up....an 88 I'm not sure about....

stabworthy · Post by **stabworthy** » 04 Apr 2019, 16:29

93Regina wrote: ↑31 Mar 2019, 22:37 This is via dealer in Phoenix: Check fitment: Volvo 1389128, Fuel Tank Sending Unit

Expand the diagrams here

There were several versions of this part. If serious, I would contact them first, with your VIN: https://www.volvopartsofphoenix.com

heads up looks like both amazon seller and the volvo of phoenix, are a bust neither one had it on their selves , even if the amazon seller shows 10 in stock.

waynegarbo wrote: ↑09 Dec 2018, 10:04

Stabworthy I got my sender out of the wrecking yard and yes it is the same. Look for the sender out of an 86' and 87'....an 85' didn't match up....an 88 I'm not sure about....

yea, we found a 87 in the a junkyard. we going to check this weekend. meanwhile im looking into a plan B and plan C.

93Regina · Post by **93Regina** » 04 Apr 2019, 20:53

stabworthy wrote: ↑04 Apr 2019, 16:29heads up looks like both amazon seller and the volvo of phoenix, are a bust

Both were the same....here is one, but it won't be cheap to be shipped from Europe

Not sure why you need one...if fuel pump works...you don't need a fuel gauge. On one 240, fuel gauge works once in awhile, and on one 940, it never works. I've done this for years....never run out of fuel so far.

I have no idea if more than one version existed stateside. Does your existing pump have a Volvo part number?