Thorny Posted April 10, 2012 Share Posted April 10, 2012 Would be very grateful if anybody could shed some light on this issue for me. It's a bit complicated so I'll explain the situation as easily as I can. The vehicle in question 1986 110 diesel. The vehicle is in the latter stages of a complete restoration. I have installed a new fuel tank as part of the restoration project, Tank mounted on small rubber bushes to absorb vibration. The original fuel gauge has been re-used. The vehicle has been completely re-wired. So, that's the background. Now for the problem... I have a new sender unit. 3 terminals on it, the same as the old original. 1- Earth 2-Gauge 3-Low fuel light With the earth terminal earthed directly back to the battery and the remaining two terminals correctly connected, the fuel light illuminates when the float is in the up (tank full) position. The fuel gauge however reads full regardless of the position of the float. So... I took the old sender off the old tank just to try it... Fuel warning light works correctly with this sender, but the fuel gauge still reads full regardless of the position of the float. I should say that prior to the restoration, the gauge and warning light both worked accurately. I have spent hours fettling different combinations of wires in case I had mistakenly put the wires onto the wrong terminals but to no avail. My limited knowledge of the dark arts of electrical wiring has been exhausted. I would greatly appreciate any help with this matter. Thanks in anticipation. Quote Link to comment Share on other sites More sharing options...
Sirocco Posted April 11, 2012 Share Posted April 11, 2012 have you tried to earth the gauge? later defenders have a daisy chain of earths across the gauges, the fuel reads full if its not connected. Not sure how it works with older models but worth a shot if not all ready considered. G Quote Link to comment Share on other sites More sharing options...
western Posted April 11, 2012 Share Posted April 11, 2012 are the gauge wires connected correctly ? earth goes to the long thread in centre of gauge rear face & jumps to each of the other gauges then into the wiring loom multi bullet connector. Quote Link to comment Share on other sites More sharing options...
Thorny Posted April 11, 2012 Author Share Posted April 11, 2012 Thanks for the input gents. So far as I understand the wiring is correct Western. The earth is daisy chained across the gauges, I have to admit to assuming that as the needle was moving the earth must be okay. I'll go back and check that thanks. I'll also double check the wires as per Westerns guidance. Once again, thanks for your help. Quote Link to comment Share on other sites More sharing options...
western Posted April 11, 2012 Share Posted April 11, 2012 on the tank unit the connections are black sleeved terminal to gauge red sleeved terminal to low fuel light the earth is the threaded/rigded stud in between the 2 sleeved terminals, a female single bullet connection is a good fit on here. Quote Link to comment Share on other sites More sharing options...
JeffR Posted April 13, 2012 Share Posted April 13, 2012 I spent bloody weeks and numerous trips to flamin A&E trying to sort out a similar problem. Turned out the tank itself had a baffle in the wrong place and the float was jamming against it..... Pattern tanks, be wary.... Quote Link to comment Share on other sites More sharing options...
Dads Toy Posted April 13, 2012 Share Posted April 13, 2012 My '95 Hard top doesn't have the low fuel warning light (blacked out in the warning light panel) and I'm changing to the later panel. Can I just change the float unit for one with the low level warning (+wiring) ? What part number am I looking for? Thanks Malcolm Quote Link to comment Share on other sites More sharing options...
western Posted April 13, 2012 Share Posted April 13, 2012 Yes plus you might need to run a wire from sender to gauge. or there might be a wire witin the loom you can use [white/slate colour code IIRC. I think this sender PRC4262 is for 90 with low fuel light. -- check with supplier before spending any cash. genuine LR version is nearly 3 times the price. Quote Link to comment Share on other sites More sharing options...
Thorny Posted April 27, 2012 Author Share Posted April 27, 2012 It's fixed!!! Sirocco, you hit the nail on the head! Thank you! The fuel gauge now reads correctly and the fuel light comes on when the tank is almost empty!!! (at flippin last!) The solution was..... A missing earth lead on the gauge was an issue With that sorted I still couldn't get either of the new sender units to work correctly. Low fuel light coming on with a full tank etc. I have managed to repair the old sender sufficiently to re-use it. Not ideal but at least everything now works as it should. Thanks for the help and advice offered. Quote Link to comment Share on other sites More sharing options...
bluehaze Posted April 28, 2012 Share Posted April 28, 2012 My fuel gauge has always lied. When it says that it is 1/4 full it really means that you have run out of fuel!!! It caught me out a couple of times when I first got it, Quote Link to comment Share on other sites More sharing options...
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