OK, I have been playing...WHY?  EDU and fuel gauge reading.
I bought a book, 3:5 Programmable EDU trip computer, M 1995.
Going by the book, I just wanted to see How far out the fuel gauge was. so I set about doing a few test.
The pump has to come out to do these test though.  (I will be putting a procedure together in the not to distance future, as soon as I get the time, and will post the link here)

The first reading I did was with the pump in place, the EDU was reading 11 gals. & the fuel gauge was mid way into the red.
First things first:.
Float should be 8mm below surface of pump, see Diag.
transmitter resistance;
Empty tank, float in lowest position 25 - 40 Ohms
Full tank, float in highest position 360 - 380 Ohms
My readings;
Reading 1 = 62 Ohms (before fuel pump removed)
Reading 2 = 32 Ohms (Float in lowest position)
Reading 3 = 366 Ohms (Float in highest position)
Reading 4 = Float nowhere near the 8 mm position
So I adjusted the float to the default (see diag)
Once back together.
Reading 5 = 109 Ohms (before fuel pump removed, I have just put it back and tightened ring down)
The EDU reading has changed to 78 miles and the gauge reading midway between the quarter and half mark.
So you see, in M97's case, the Ohms readings are well within spec, but the float was giving me a false readings on the gauge and EDU.
Not going to save me any more petrol, but will show more accurate reading.

http://i158.photobucket.com/albums/t97/saviour_54/saab%20edu/scan0002.jpg
http://i158.photobucket.com/albums/t97/saviour_54/saab%20edu/scan0001.jpg

Readings (app)

32 Ohms = Empty
68 Ohms =  Quarter
167 Ohms = Half
251 Ohms = Three quarters
366 Ohms = Full

any comments ?