Defender Tdi Fuel Gauge easy fix

[rover-56]

I have had a vague reading fuel gauge for a while, and did the usual wiring and earth point checks. I also found a dodgy in line connector on the gauge. All good. That fix lasted about 2 weeks.
So looked like I needed a new sender unit.
Being the cheapskate that I am I decided to take it out and have a look first.
Found that the printed resistance strip to be in good condition, as was the sliding contact blade,
but the clearance of the float pivot pin in the housing (both moulded plastic) was quite large, maybe wear, or wide manufacturing tolerance, allowing the contact to float away from the resistor.
I rolled a strip of thin brass shim around the pin and clicked it back in. Much better, blade stayed in contact however I jiggled the float.
The gauge has always read empty when there was 25l of fuel left, so I also bent the wire float arm down so the float was level with the end of the pickup tube.
Now the gauge is steady and reads empty with 5l of fuel left.
The actual fix was quicker than writing this, the hardest part was getting the bayonet retaining ring back in.
A few s** and b** words seemed to help.

So have a look before you buy a sender.

Terry

[travelrover]

I have had a vague reading fuel gauge for a while, and did the usual wiring and earth point checks. I also found a dodgy in line connector on the gauge. All good. That fix lasted about 2 weeks.
So looked like I needed a new sender unit.
Being the cheapskate that I am I decided to take it out and have a look first.
Found that the printed resistance strip to be in good condition, as was the sliding contact blade,
but the clearance of the float pivot pin in the housing (both moulded plastic) was quite large, maybe wear, or wide manufacturing tolerance, allowing the contact to float away from the resistor.
I rolled a strip of thin brass shim around the pin and clicked it back in. Much better, blade stayed in contact however I jiggled the float.
The gauge has always read empty when there was 25l of fuel left, so I also bent the wire float arm down so the float was level with the end of the pickup tube.
Now the gauge is steady and reads empty with 5l of fuel left.
The actual fix was quicker than writing this, the hardest part was getting the bayonet retaining ring back in.
A few s** and b** words seemed to help.

So have a look before you buy a sender.

Terry

I suspect my 300 Tdi also has a dodgy sender. It stays on full for a long long time and when reading between 1/2 and a 1/4 full it takes around 60 liters to top up. The PO told me it had a replacement tank, so I had assumed a larger capacity unit. But maybe not. I need to investigate further.

[rover-56]

The float pivot is towards the top of the tank so the gauge will fall slower initially then quicker as it gets below 1/2.

All the parts are easily accessible once you get it out. I used a pair of pointy pliers to separate the 2 float spindle retainers.

Terry

[VladTepes]

My gauge appears to be stuck on 'full'. I suppose I'd better do some troubleshooting... where to start?

[Phil B]

If it stays on full it could mean the sensor wire is shorting to earth
Or the connector on the sender has fallen off and is shorting on the tank or sender unit