Weird gauge problems

Just trying to sort out all the little problem on the mk2, there's a long list of them

2 issues with the gauges.

1st being the coolant temperature, it will occasionally give a reading on the gauge and then the needle will fall back to zero and then may jump up again or just stay put. It also never reads the correct temperature either (I'm guessing it should be half way up the gauge)

The 2nd is the fuel level gauge, I know the tank is full as I had the sender out of it to look, but the gauge will only read about 3 quarters full and I never know when it empty. At first I thought it was completely messed up as the engine started cutting out as if it had ran out of fuel even though there was some in there. This however is another issue which I've put down to the fuel pump.

So basically both gauges display under what they are supposed to. And as both don't work I figured it must be something to do with the clocks, the rev counter and lights etc all work fine.

Anyone know what the problem could be? Or is it new clocks time?