Fuel gauge defect?

[LucN]

Hi,

Today i measured between the two connectors of the fuel tank 125 ohm, on the fuel gauge i mesasure 127 ohm, the fuel gauge shows an empty tank, while its neerly full.
If i remove one of the wires from the connectors, nothing happens.
Does this means, the fuel gauge is defect?

thx for your response

Luc

[RoyBatty]

Are the wires reversed?

[spider2081]

On my 1981 Spider if I disconnect the light blue wire from the sender the gauge reads empty with the ignition key on.
Grounding the light blue wire with the key on makes the gauge peg.
It is very common for the fuel tanks to rust where they meet the trunk floor and loose their ground. I add a ground wire under one of the sender nuts to a good ground. This cures lots of gas gauge problems.

[LucN]

Hi

even if I reverse the wires, nothing happens (the gauge still shows empty....)

are there a few easy steps to follow to ditermine, the sender or the gauge is defect?

Luc

[azruss]

neither wire are a ground. The ground is thru the gas tank studs. one wire is the gauge the other is the idiot light.

[LucN]

is it correct (as a test) that if one of the tank wires is on the ground, the idiot lamp should work?

Luc

[spider2081]

I believe grounding one of the wires will lite the idiot light and grounding the other should make the gauge needle peg beyond full. Do not leave the gauge pegged too long or you could damage the gauge.

[bobplyler]

It's usually the fuel level sending unit. It's almost never the gauge.

[LucN]

i did some tests today,.....
grounding one (or both) of the tank connection give no response of the gauge

maybe its best to replace both sending unit and gauge?

grtz,

Luc

[spider2081]

I think you need to inspect the back of the fuel gauge. There needs to be power (12V) from the fuse panel for the gauge and idiot light to work. On my 1981 the gauge has a connector maybe it has become disconnected.

[LucN]

Hi,

yesterday, I've replaced the sending unit, the gauge still points empty while the tank is nearley full.
I've replaced the gauge with a used one I've bought last week, the result is identical
fuse = ok,

all sugestions are appreciated to solve this mystery

Luc

[DieselSpider]

Hi,

yesterday, I've replaced the sending unit, the gauge still points empty while the tank is nearley full.
I've replaced the gauge with a used one I've bought last week, the result is identical
fuse = ok,

all sugestions are appreciated to solve this mystery

Luc

When you replaced the gauge did you first verify that it was good and then once installed that there was power going to it using a meter or a test light. This would be the first test. Next you can test the gauge as installed by connecting momentarily the other connectors on the back of the gauge to the ground and then on one the idiot light should light while the other will peg the gauge indicating a good gauge. You can bench test the old gauge this way too and you can also test the old gauge and sender by hooking them up outside the car. Next connect the two wires from the sender together and with a meter read continuity between the gauge ends of the wires and if none then one of the wires is broken somewhere so each one needs to be checked individually by connecting one end to ground and then checking continuity to ground on the other end.