Fuel sender testing with multimeter

[leggattr]

So testing my spare fuel sender tonight as the one in the nova keeps reading full and the only way I can get it to read correctly is by earthing it from the level rod. When it’s attached to the sender body it only reads from either full (hitting the stop mark on the body) or empty (again touching the body).
Any ideas?
https://uploads.tapatalk-cdn.com/20190123/fb1b12c04c817305683390e80eb4994f.jpg


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[Stuart]

Its a simple resistor.
One side will probably be grounded and the other to the clocks.

[Jonesfach]

Your black lead should be on the earth connection of the sender as far as I remember. It's on the front by the red lead.

i put some resistances from the sender on here a few years back. 90ohms to 270ohms or something like. I will try and find my post....here it is!


Best way to find out whether it is a sender or not is get hold of a cheap resistance meter or multi meter.

disconect the two leads. Put the meter on ohms and take the reading. If tank full it should read 40 ohms and if empty the reading should be 240. Hence half tank will be about 140.
i changed mine the other week for a brand new one and took the trouble to get the readings before I fitted it.
a cheap multimeter will save loads of messing about , not to mention the frustration!

[Jonesfach]

Oh spray some wd40 seems to help. I put some on my old one and it seemed to work again when I tested it after removing it. Didn't fancy putting it back in though as I had a new one.

[GT1965]

So testing my spare fuel sender tonight as the one in the nova keeps reading full and the only way I can get it to read correctly is by earthing it from the level rod. When it’s attached to the sender body it only reads from either full (hitting the stop mark on the body) or empty (again touching the body).
Any ideas?
https://uploads.tapatalk-cdn.com/20190123/fb1b12c04c817305683390e80eb4994f.jpg


Sent from my iPhone using TapatalkSounds to me like a dodgy earth.....

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[leggattr]

I did find this and took a picture of it. The sender body has corroded a bit so may be stopping it connecting well. I’m pulling the other of the car tomorrow to see if it’s any different



Your black lead should be on the earth connection of the sender as far as I remember. It's on the front by the red lead.

i put some resistances from the sender on here a few years back. 90ohms to 270ohms or something like. I will try and find my post....here it is!


Best way to find out whether it is a sender or not is get hold of a cheap resistance meter or multi meter.

disconect the two leads. Put the meter on ohms and take the reading. If tank full it should read 40 ohms and if empty the reading should be 240. Hence half tank will be about 140.
i changed mine the other week for a brand new one and took the trouble to get the readings before I fitted it.
a cheap multimeter will save loads of messing about , not to mention the frustration!

[leggattr]

Connecting it the the yellow earth wire on the body doesn’t seem to work. Only finds resistance when the level arm touches the stopper at empty or full. I can only assume it’s a poor earth.

[leggattr]

So both senders are working as they should. But for some reason it starts to give a full reading whenever it’s in the tank. I’ve checked the resistance on the back of the fuel gauge which seems to read fine. Can only assume an earth issue between sender and gauge? Any thoughts?