Fuel Gauge reading wrong

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Powles89

Member
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11
Location
Norwich
Hi I have recently purchased 2003 Discovery 2 TD5.

The fuel gauge has been a bit temperamental and have read up on usual tricks to get things working with no improvement. So I have bitten the bullet and bought new pump and sender since installing new pump the gauge starts to creep up to full which is the level in the tank and drops back to below empty with fuel light on.

Has anyone else had this problem or have any information that would help

Many Thanks in advance
 
cheap pump or decent make,the last time i came across that it was a fault sender on the pump ie the arm wasnt making full contact with the resistor board,
 
I think the second is at the front of the tank, (small arm and thin hands required)
Each sender reads and the total quantity is the sum of the two
 
May be D3 , was one in workshop I was in getting inaccurate fuel reading (was sensor in front of tank)
 
If the sender relies on a float, which most do, it could simply be a pinhole in the float.
Have never taken one out, (on a Landy) so don't know but if this is the case then a simple repair should fix it, blob of some non-dissovable in Diesel, or petrol, glue, eg araldite.
It's late so I haven't even been bothered to look to the top if the thread to see what fuel you use.
Sorry!
 
Had a tinker again last night and I’ve checked that the float resistance increases and decreases as it should and I have output at the top of the pump and through the electrical connection. So either the gauge is knackered or there is an open circuit on the wiring between pump connection and fuel gauge. Do the gauges suffer with any problems?
 
Powles89 said:
Had a tinker again last night and I’ve checked that the float resistance increases and decreases as it should and I have output at the top of the pump and through the electrical connection. So either the gauge is knackered or there is an open circuit on the wiring between pump connection and fuel gauge. Do the gauges suffer with any problems?
Click to expand...
You are on the right track, the circuit goes through two connectors, unplug the pump, make a bridge across pins 2-3(pink/black - green/black wires) and check continuity in connector C0230 across pins 13 -14(same colour wires), check against earth too to rule out a short to ground... if you have continuity to pump's plug the problem is in the cluster, if no continuity or short to ground then it can be a nightmare to find the problematic point, then we'll speak again

C0230.jpg
 
sierrafery said:
You are on the right track, the circuit goes through two connectors, unplug the pump, make a bridge across pins 2-3(pink/black - green/black wires) and check continuity in connector C0230 across pins 13 -14(same colour wires), check against earth too to rule out a short to ground... if you have continuity to pump's plug the problem is in the cluster, if no continuity or short to ground then it can be a nightmare to find the problematic point, then we'll speak again

View attachment 201410
Click to expand...

Thank you for your quick reply and advice nice to know that I’m on the right track will give this a go and post the results accordingly
 
When you took the sender out, did you shake it and did it sound like it had fuel inside the float?
Have you tried suspending it in a bucket of fuel and seeing if the float rises and falls, i.e. actually floats?
Moving it up and down, and seeing if you get a signal from it, only shows that the signal is generated. It doesn't show that the float floats, if you see what I mean!
 
Stanleysteamer said:
When you took the sender out, did you shake it and did it sound like it had fuel inside the float?
Have you tried suspending it in a bucket of fuel and seeing if the float rises and falls, i.e. actually floats?
Moving it up and down, and seeing if you get a signal from it, only shows that the signal is generated. It doesn't show that the float floats, if you see what I mean!
Click to expand...

I haven’t tried floating it in a bucket of fuel like you say but I can confirm there was no fuel in the float as most of it ended up in the boot :mad:

But may be worth pulling out again just to make sure it floats stupidly I assumed that a brand new part would be perfect but I’m slowly realising nothing is ever perfect
 
Powles89 said:
I haven’t tried floating it in a bucket of fuel like you say but I can confirm there was no fuel in the float as most of it ended up in the boot :mad:

But may be worth pulling out again just to make sure it floats stupidly I assumed that a brand new part would be perfect but I’m slowly realising nothing is ever perfect
Click to expand...
You could even find they've "forgotten" to fit the float! Tell us, do you have the old sender unit? If so you could plug it in and use it to test your gauge. If the gauge then works you know it is the sender.

If there is fuel in the float and it is only a pinhole, then it may not be obvious and it may only come out with vigourous shaking.

Surely @sierrafery , if he takes the sender out and manually moves the float to the full position with it still plugged in then surely that would test the gauge wouldn't it? I appreciate he would still need to make the connections, but it not being a steel tank he wouldn't have to worry about an earth to it, would he?
 
Further developments this afternoon I can confirm that the gauge is not faulty nor is the sender unit it appears to be a fault on the wiring in between the two I had no continuity from back of dashboard to sender unit. However I made a bypass cable simply plugged in to the correct terminals on sender unit to correct terminals on multi plug at back of dashboard. This initially got the gauge reading but then soon went to its original state of reading wrong. I believe this happened because it received the signal correctly but then also sensed the fault within the existing wiring. Would I be correct in saying that if I isolated the fault section of wire and ran my temporary again this would cure the fuel gauge problem?
 
If you didnt disconnect the original wiring when you connected your bypass and the fault came back the ony explanation can be that on the old wiring is a short to ground cos if it was just simply interrupted the symptom should have dissapeard... did you check the original wires against earth too as i recommended first time ?
 
I did check the original wires to Earth but didn’t receive anything to suggest that there was a short. However I naturally assumed that with an open circuit somewhere on the wiring that one end would be touching metal work some where.
 
I also am not sure about any of the wiring on this vehicle it appears whoever owned it before me has just cut and spliced wire in all over the place and cut connectors out all over the place
 
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