fuel gauge or sending unit in '91 w/Regina?

I just got a '91 740 wagon after my '92 240 was involved in an accident. I'm
still getting accustomed to the wagon and the Regina system I suppose.
The owners manual states that the fuel tank holds 15.9 gallons. I have yet
to add more than 11.5 even when I thought I was almost empty.
And when the gauge gets almost to the empty mark it starts hesitating when I
let off accelerator and then accelerate...my 240 with Bosch system never did
this.
I have even run out of gas because the needle was close to empty but the
warning light was not yet on.
My question : Is there a problem with the sending unit in the tank or what?
It does not seem to be keeping accurate readings especially on the full end
and empty end. Surely it does not have a smaller gas tank than listed in
manual.
Input about this matter will be appreciated. I certainly do not want to run
out of gas again.
James B.

 

You will need to take the pump & sender unit out of the tank to check the
fuel pick-up strainer and the pipe coupling from pump to main fuel feed.
Your car has only one pump which is in-tank and more powerful than the
in-tank pump on the two pump system (LH). The tank should hold 60 Litres
which is about 13.2 gallons (imperial) or 15.85 gallons (US). I suggest that
the low-fuel warning switch or the indicator lamp in the gauge is not
working. It should show when approx 6 Litres (1.5 US gallons) of fuel remain
in the tank. The sender probably has a contact problem which causes the
wavering symptom.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).