Thread: Very inaccurate fuel gauge

yep. when bro first got the TD5, did the same thing.
Then it started giving driveability issues(losing power, rough starting.. blah blah), and seemed like a fuel pump issue.
Fuel pump and gauge float usually come as a single expensive package(but you can get just the pump and rebuild the 'unit' yourself too if you search ..

So anyhow, in the arduous process of tracking down the bad running issues, replaced the fuel pump assembly and the gauge returned to a more accurate display mode.

I don't know if you could try to restore the resistor element in the sender section, but my guess is it wouldn't be worth the bother.

What I could recommend if you want the gauge working more accurately is to locate a cheapie fuel pump unit(you can get them in the $70 range), and all you really want(need) is the new assembly unit. The pump itself is almost certain to be some rubbish Chinesium concoction that won't last more than a few minutes .. so expect to turf that immediately. You could reuse your fuel pump unit or locate a proper fuel pump to fit into the cheaper body.

I can't remember if the actual float/resistor section was removable without breaking it .. but that could also be another way to restore the fuel gauge accuracy if it is too.

Originally Posted by shayne86

Does anyone have any experience with their fuel gauge being rather inaccurate? For example my v8 only does about 440kms to a tank, yet the gauge won't move from full until about 150kms and then hit "half" at around 300kms. From "half" there its literally only 100-ish kays until fuel light. Seems waaaaay out.

Anyone else had this or experienced this? This is my first landy so ive got nothing to compare it too. I've had cars with less than perfect gauges but this seems a bit silly. Wondering if i should be looking at replacing the sender unit/pump

My D2a did the exact same thing.

Originally Posted by trout1105

My D2a did the exact same thing.

I should have stated that mine is a d2a facelift model. Must be normal then

Originally Posted by shayne86

I should have stated that mine is a d2a facelift model. Must be normal then

Yeah, I reckon not an unexpected issue from a 20odd year old vehicle tho.

Bear in mind, that due to the shape of the tank, the first half will always give considerably mor range than the second half.

I just thought mine got worse because i made the tank slightly concave bouncing over rocks one time

I just recently replaced the pump only into the existing assy. I can confirm that you can easily remove the fuel gauge sender unit from the main assy. so it is possible to replace. My car is a face lift td5. As you may well know, you can buy new the assy piece of the pump unit separately but it is rather fiddly to fit a new pump into that assy. Can be done though. I posted some notes about this recently in the "What happened to your disco today" thread.

BTW, my car does hover on "full" for about 100km but then moves away from that and indicates remaining fuel quite accurately over the rest of the range.

I don't know if the Disco tank is similar to the Defender, but I found a simple way to improve the accuracy of the gauge.
I had always been able to drive well over 100km before it moved off full. Although the bottom half gave me less distance than the top half, it wasn't as bad as yours.
I had to replace the tank recently and when refitted, the gauge indicated something that I knew was way off. It was obvious that the float on the end of sender unit arm was resting on the bottom of the tank, so it would indicate about 1/4 if the tank was empty.
Because of the way the sender unit is fitted to the side of the tank, a tiny change in the slope of the spot where it fits means a huge change in the position of the float at the end of the very long arm inside the tank.
I just unclipped the sender unit from the side of the tank, bent the wire supporting the float and found that my guess about how much to bend the arm was spot on.
Now after about 50km, the needle has just moved off full and it shows 3/4, half, and 1/4 when there is almost exactly that amount in the tank.
As I said , I don't know if the Disco tank and sender are similar, but someone else here will know.
It is possible that you could improve the accuracy as I did just by bending the long bit of wire supporting the float.