tuko Posted May 30, 2021 Share Posted May 30, 2021 This past winter the fuel gauge began giving me wrong readings. Fully fuelled I get a full tank reading then as the fuel level goes down the guage sinks accordingly til half tank and it then stops there. From half tank to empty I have no idea what or where the level is. The guage stays rock solid at half tank. I checked and cleaned the contacts on the tank bit to be honest they didn't appear to be wonky. With power the guage did go up and down from the sender unit. ( I do have 3/4 tank at the moment ) Could a bad gauge give these wrong readings after half tank? Todd. Quote Link to comment Share on other sites More sharing options...
steve b Posted May 30, 2021 Share Posted May 30, 2021 If it works when removed and connected to gauge wire with an earth wire by manually moving the float arm then it is probably the earth through the tank so add an earth wire from the sender to somewhere with a known good earth Steve Quote Link to comment Share on other sites More sharing options...
DC_ Posted May 30, 2021 Share Posted May 30, 2021 Having just replaced my 110 tank and sender unit I now have a fully functioning fuel gauge. previously mine would get to 3/4 full ad then Bob about like a SWR meter on a CB radio. Could be earth or a faulty sender. Good luck Quote Link to comment Share on other sites More sharing options...
tuko Posted May 30, 2021 Author Share Posted May 30, 2021 Thanks guys, tomorrow I will be grounding the sender unit, then cross my fingers it's just a ground issue. Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 31, 2021 Share Posted May 31, 2021 Some pattern part sender units have excessively long float arms. It’s possible that the float is catching on an obstruction or even contacting the tank bottom when the arm is half way through its arc. The fuel and temperature gauges over-read if they aren’t well earthed from their casings to the bulkhead, and so it is possible that an over-reading gauge with that fault was made to read the top of the tank correctly by someone bending the float arm so that the potentiometer is in mid range with the float at the top of the tank, reaching the bottom of its motion as the float reaches the middle, with the gauge still over-reading. Quote Link to comment Share on other sites More sharing options...
monkie Posted June 1, 2021 Share Posted June 1, 2021 The best thing to do is to remove the gauge and sender from the vehicle and wire them up to the battery remembering to earth the gauge casing. Ensure the gauge reads full, half and empty correctly so you know all works as it should do. Then when you reinstall ensure the sender isn't being obstructed so it can travel freely and the wiring and terminals are all in good condition with good earths. Quote Link to comment Share on other sites More sharing options...
steve b Posted June 1, 2021 Share Posted June 1, 2021 The gauge case does not need to be earthed and the voltage stabiliser would need to be in the supply to the gauge Steve Quote Link to comment Share on other sites More sharing options...
tuko Posted June 1, 2021 Author Share Posted June 1, 2021 6 hours ago, steve b said: The gauge case does not need to be earthed and the voltage stabiliser would need to be in the supply to the gauge Steve In the fall I removed the sender unit from the tank when I was offroading because I had fuel starvation but the gauge was showing full. It turned out to be a pinched line under the landy but after removing the sender unit I've had this problem. Funny thing is the voltage gauge doesn't show properly either. ?? What you mentioned earlier Steve got me thinking that maybe I did not have the sender unit properly grounded so I did as you suggested and now have a ground to the sender unit. Still though the voltage unit is showing wrong and still till I run the fuel level down I will not know if the fuel sender unit is now working properly. Todd. Quote Link to comment Share on other sites More sharing options...
steve b Posted June 1, 2021 Share Posted June 1, 2021 Where have you got the voltage gauge live and earth ? Ideal live would be the white off the ignition switch and the earth direct to the bulkhead metal somewhere although in theory the earths on the back of the instruments should be fine Have you manually cycled the sender float arm from empty to full out of the tank with the feed connected and a good earth to see what the gauge does ? Steve Quote Link to comment Share on other sites More sharing options...
tuko Posted June 2, 2021 Author Share Posted June 2, 2021 It appears that I might have found the problem, the plan today was to remove the sender unit again to test and make sure that it does actually go through it's full range on the gauge but I couldn't get it out......the float was catching on the fuel return tube. I must have in the fall bent the float rod just enough for the float or the rod itself to catch on the return tube. Some fiddling around and the float now "appears" to have free movement and clear of the fuel return tube. Of course I have to run the tank down to actually see if I solve this. 1 Quote Link to comment Share on other sites More sharing options...
tuko Posted July 2, 2021 Author Share Posted July 2, 2021 I've gotten to the point where I'm confident that I can drive a fair distance without guessing anymore. Clearly me playing around in the fuel tank while in the woods was the reason why the float was catching on the drain pipe. Vacation to northern Sweden next week, will be interesting to see how many miles I can get to a tank after me "adjusting" the float wire. I have noticed already the first quarter goes down faster than previous. Thanks for all the tips and suggestions. Todd. 1 Quote Link to comment Share on other sites More sharing options...
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