Fuel Sender or Fuel Gauge, which is more likely at fault?

I've run out of fuel twice in my 300tdi because the needle seems to stop just after it dips below half way.

Is there a way to test the signal from the sender?
Is there a way to fake a signal to the gauge?

Which is the most likely to be at fault?

Ign off gauge empty? Probably the sender.
Run a wire from the neg off the battery to the terminal on the gauge that the sender normally goes to and it should read full with ign on.
All the sender does is alter the resistance going to the gauge to move the needle. You will probably find broken wires on the sender windings if you remove it from the tank.
If you have a multimeter you can confirm it.
Think that's about right ?

Just read your post again..
Could be the sender float is getting caught up inside the tank and not dropping down low enough.

Sounds right to me.

Col

I’ve had fuel sender problems. I replaced mine as it was fairly cheap, recently had it back out as I learnt the hard way it needs calibrating first. No signs of damage to the old sender, I presume with age it just packed up internally.

Mine works but even working I don't rely on it. I go by mileage and reset the trip meter after every fuel up. The gauge gives you a guide but I would not trust it not let me run out of fuel.

Rather than post a new topic, would appreciate your advice about the exact opposite. I replaced the sender unit a couple of years ago and since then, the gauge will only show 3/4 of a tank when brimmed. Should I fish it out and bend the wire a little bit?

reiny said:

Rather than post a new topic, would appreciate your advice about the exact opposite. I replaced the sender unit a couple of years ago and since then, the gauge will only show 3/4 of a tank when brimmed. Should I fish it out and bend the wire a little bit?

Click to expand...

Yes. You haven't got much to lose. Either it will work, or it won't. If it doesn't you can always bend it back again and look at the gauge.

reiny said:

Rather than post a new topic, would appreciate your advice about the exact opposite. I replaced the sender unit a couple of years ago and since then, the gauge will only show 3/4 of a tank when brimmed. Should I fish it out and bend the wire a little bit?

Click to expand...

Mine did exactly that after I replaced the seal. I§ve just replaced the fuel pump and whilst taking out the old pump I noticed the top half disconnectef rom the bottom half. Possible cause of the bad float. After new pump fuel gauge works fine.

Mine currently does exactly the same, only reads up to 3/4. What I didn’t check is the upper stop, so I’m hoping if I bend that tab up a bit it’ll let 5he float go higher And read full

Oops! I take it this isn't supposed to happen?

Managed to Q-Bond it back on. Seems solid enough.