fuel tank senders

[tourer-dan]

I posted up a while ago about a dodgy fuel guage.
I had the guage out last week whilst I put in the OBC and everything seemed fine, the needle wasn't bent and it travelled smoothly from empty to full.
So I took the senders out of the tank yesterday and noticed the fuel tank was empty on one side but not the other. The dry side was the left side and the right (pump) side had about 10cm in the bottom. At this point the guage showed just above empty. When I lifted the left sender it was dry and made no difference to the reading. Turning it upside down sent the guage to halfway. With the left sender back in, I lifted the right one. The guage slowly dropped (as it drained) and then the light came on (I've never seen the light on before) Turning them both upside down sent the guage to full. I tested the resistance on both which went from.60 to zero as the float moved up. I substituted the pump sender for another one and put it all back together.
I have another touring in the garden which I have for spares. both sides of the tank are equally full and the guage works better, ie, the light comes on when the guage gets to the bottom of the red.
So I'm at a bit of a loss.
I'd like to kow how the fuel transfers from one side of the tank to the other, as if there was no device, the fuel tank would empty on the pump side leaving some left in the left side. Mine seems to be emptying one side first whic is upsetting the fuel guage.

[Brianmoooore]

I'd like to know the answer to this one as well! I've asked about it before but have never had a convincing answer.
Some tanks have a little pipe across from one side to the other under the prop, but others don't.
Obviously a certain amount of petrol would slop from the left side to the right in normal driving, but surely this isn't the only mechanism.
Your description and testing of the tank senders sounds about spot on.
The low fuel light shouldn't come on untill the gauge needle is right on or past the lower end of the red painted bit on the dial.