1977 280z "Fuel" warning light always on

[Dave WM]

3 hours ago, DramaZed said:

It was working the last 2 months. Started acting funny yesterday when I filled up the tank. 

ok so its brand new, two months old, works perfect, as in it would come on when tank was nearly empty. I mean I rarely see mine come on as I rarely get down that low on fuel. so approx how many times did it work? off and on at low fuel?

describe the way it came on, suddenly or slowly when it was working.

Edited August 5, 2021 by Dave WM

[DramaZed]

It worked 2 tanks when running low on fuel. 

Crank the car. The light slowly builds up to full brightness. I would say about 20 seconds to one minute max. I went to get fuel when it was lit and indicated low then I came back with a full tank and it’s been doing it every since. (Last 2 days)

[Dave WM]

30 minutes ago, DramaZed said:

It worked 2 tanks when running low on fuel. 

Crank the car. The light slowly builds up to full brightness. I would say about 20 seconds to one minute max. I went to get fuel when it was lit and indicated low then I came back with a full tank and it’s been doing it every since. (Last 2 days)

ok this is a long shot..

IF the can the thermistor sits in gets plugged up by junk in the tank, I suppose its possible the small holes in the can could become blocked. this would prevent fuel from cooling the thermistor, allowing heat to build and resistance to drop.

I would pull the sending unit, look it over real well for the small holes I mention, maybe even use a small exacto blade to open them up a tiny bit, and try it again. IIRC from some of the new units being made, the holes may be the issue, esp in a old tank.

after clearing/opening up the holes test it before reinstalling. you want to see bubbles come out of the can when immersed into a fluid, then drain out again when removed. I presume the can and hole size is setup to act as a damper slow the on off process.

 

Edited August 5, 2021 by Dave WM

[DramaZed]

5 hours ago, Dave WM said:

geez this keeps coming up.

I would recommend you pull the unit out of the tank and bench test it with a 12v source and the light used in the car. could be you just have the wrong light, pulling too much current causing the thermistor to run away.

Yeah it’s been working. Just recently happened