85 280i fuel gauge wiring

[kestor]

Greetings!
Been cruising/lurking here for a bit, lots of helpful information!

1985 TVR 280i (with a 2.9 Merkur...)
Recently sent my disfunctioning fuel gauge off to be checked and now can't find my picture of the wiring hookup
Anyone have the correct connections they can share?

[Jon280]

Hi

Here are a couple of pictures from my 1985 280i, connections to the rear of the VDO fuel gauge. Hope they help!

Top connection (used for illumination, think the bulb comes out if you rotate the connector)


Bottom connections (Top wire is Green with black stripe, lower wire is plain green, and the side one is black)

[kestor]

Thank you!
Exactly what I was looking for!

[kestor]

Well, presuming the gauge does work (sent off to be checked/repaired) I must have other wiring problems...
With the gauge in wired as shown, I connected the two wires off the sending unit together and get no reading at the gauge.
As far as I know only one wire from the sending unit actually goes to the gauge, the other goes to ground somewhere. Is that correct?
Would anyone have the wiring path from the sending unit to the gauge?

[RCK974X]

Generally speaking power->gauge->sender->earth

If it's a Smith's gauge then power->regulator->gauge->sender->earth
as they are calibrated for 10 volts.

[phillpot]

Terminals may be marked differently but it's as simple as this.................

[kestor]

Thanks for the replies
I should have stated VDO gauges

There are 2 green wires and 2 black wires in the connectors at the back of the gauge.
I would guess the gauge is hooked in to the other gauges somehow.
The only other gauge that does not work is the oil pressure. But I believe it is not connected.

Where does the ground wire from the fuel sending unit end up?
It travels with the handbrake cable toward the front of the car somewhere.

[RCK974X]

Yeah, the joys of a fibreglass car. You ain't got no steel body, so you need earth wires. And dodgy, corroded earths can cause some truly WEIRD affects....like, say, turning on the side lights makes all your gauges read higher...(or lower).

Don't know where the wire goes, could well be to handbrake as nearest earth point....My sender had a wire through one of the fixing bolts to the chassis (one of the bush bolts)

[kestor]

Wellllll,
For whatever reason by whatever means my fuel gauge works!!!
I crawled underneath and had the mrs run the power/key. When I disconnected the two wires at the sender from each other the gauge read full.
Not being confident that she was doing it right (shhh, she'll hear me), I repeatedly connected/disconnected the wires in different ways.
Satisfied that something was going on I plugged the wires back in to the sending unit and crawled out.
Knowing that it was running low on fuel I headed to the station and watched in amazement as the gauge read full!
Having checked the sending unit previously and not getting any reading, I now have several hours that I had budgeted for winter work replacing the sending unit for other things.
And yes, I did consider buying a lottery ticket while I was out

Thanks again for all your help!!

[RCK974X]

Do check gauge drops as you drive, otherwise it could be a short somewhere, and it's embarrassing to run out of gas (and a PITA)