The only thing i can see that could be related, is fuel level memory of the dash gauge. This should sort itself out on the next fill up though
If the transfer pump isn't working then it's known for the gauge to get stuck on 1/4 full even when you 'run out' of fuel
 
On a slight tangent, i don't know about the earlier models, but 2010+ will introduce a misfire when you get very low on fuel to give you a warning. The computer won't allow you to completely run out of diesel
 
A further update (as I know us folks on forums love to follow a thread though to conclusion). The gauge is definitely working - the more I've driven the car lately, the needle is definitely dropping. It has moved from 1/8 below half (where it was maxing out when filled with fuel) to 2/8 below half.

I've pretty much convinced myself that it is dropping at a slower rate than usual - which could point to a fault with one of the two level sensors in the saddle tank - my logic being that if it is displaying the average of one sensor working correctly and one duff sensor, then it would fall at half the usual rate. I haven't backed up this theory with any data though - will have to brim the tank and actually take some mileage readings to do that. I think that's the next step here.

All of that may still be incorrect - it may just be a calibration issue as others have pointed out. To be continued...
 
A further update (as I know us folks on forums love to follow a thread though to conclusion). The gauge is definitely working - the more I've driven the car lately, the needle is definitely dropping. It has moved from 1/8 below half (where it was maxing out when filled with fuel) to 2/8 below half.

I've pretty much convinced myself that it is dropping at a slower rate than usual - which could point to a fault with one of the two level sensors in the saddle tank - my logic being that if it is displaying the average of one sensor working correctly and one duff sensor, then it would fall at half the usual rate. I haven't backed up this theory with any data though - will have to brim the tank and actually take some mileage readings to do that. I think that's the next step here.

All of that may still be incorrect - it may just be a calibration issue as others have pointed out. To be continued...
I never rely on the gauge in any car, I always brim the tank and reset the mileage trip so I know exactly how far I can go before I need to refill.
 
I will post the last page to the doc I posted earlier that I missed:oops:
It shows you can check resistance of the sensors in full and empty, so you should be able to check if 1 is duff.
I am guessing you could get to the connectors under the access holes.

J
 
A quick update on this - am booked in to my local RR indy in a few weeks to look at the sensors/senders. He, like a number of you, thinks that the issue is likely to be a failure at that end causing issues with the "averaging"/calibration of the fuel level, so the gauge is just giving a duff reading.

Interestingly, when I now brim the tank, the fuel reading shows 2/8 rather than the previous 3/8!
 

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