Fuel gauge readings

[UKSquarebody]

Hey all,

My 87 R10 (dual tanks) has a pointless fuel gauge - can anyone help?!
Both tanks do the same thing, which is.......
If I put say £40 of fuel in each tank - the gauge will read half full.
It will then drop away as a drive.
Now, before the jokes - I know MPG is not awesome - but if I leave my house in the morning for work, it will read half full. By the time I am at work (5 miles away) it will read between 1/8th to 1/4 - fluctuating all the way.
Time to come home, it will read around half a tank, and drop away again by the time I am home.
Both fuel tanks/senders are doing the same thing.

Over the course of say 10 miles - the gauge will show anything between half full and almost empty - changing all the time.

Any clues/fixes?!

Cheers,
Keith

 

[fast 99]

Would suspect a connection is heating up creating resistance. Could be power or ground. Look at grounds first.

 

[bedwards]

There are no baffles in the tanks

 

[UKSquarebody]

Thanks guys, I will check the grounds.
No baffles - I would expect inconsistant movements - but this is very consistant. Same thing every day - starts half full, slowly works down.
If it were just baffles - the fuel level would rise and fall - this just consistently falls.