The copper/brass wire is only for the low fuel light. It can be completely missing (as it is on my wife's 300D) and the gauge will still work. Most likely, your float is sticking on the rod. You can check operation with the sender out of the tank, either hooked up to the gauge or to an ohm meter. It is less than 5 ohms at the top and between 50 and 100 (depending on model) at the bottom. The float should easily slide from top to bottom as you turn the sender over.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

I thought the low fuel light is triggered by some kind of contact on the bottom.

I need to pull mine, it's very erratic. I go from below empty to correct measurement and stuff in between with the bumps on the road.

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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

thanks to all for input on this issue...will pull out and repair/clean up again over weekend....if this doesn't work, does anyone have any ideas of WHERE to secure another working, used unit that does not cost $150+ over the internet?????

Yes it is and it goes thru the copper/brass wire. The Gauge uses the silver (nichrome) wires.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

Teddy49-I have a PNP unit from a 83 SD I cleaned up and got working-but never used. PM me if you wish it