rovernut Posted March 11, 2013 Share Posted March 11, 2013 Until this morning, my fuel gauge has been reading spot on. When I got to work it was reading FULL (on the mark and not above it as it would be if earthed)I know that I have approx 1/4 tank of diesel. On the way home, it returned to its proper reading for a short time and then climbed to 3/4 reading.I am guessing it could be an earth problem / bad connection somewhere. I have no idea if it is related but the water in fuel light came on a couple of weeks ago and I don't have a sensor fitted. I soaked the plug in WD40 and the problem was gone. Is this in the same wiring loom ?Another question, Is the fuel warning light separately triggered because it would be useful to have some indication of fuel state. Quote Link to comment Share on other sites More sharing options...
SORNagain Posted March 11, 2013 Share Posted March 11, 2013 Lots of salt on the roads at the moment. It might be that you have salty water in the connections somewhere and it is giving you a (surprisingly low) resistance to earth, but still higher than you would get with a short. Quote Link to comment Share on other sites More sharing options...
rovernut Posted March 14, 2013 Author Share Posted March 14, 2013 new twist today. Not knowing what the fuel state is, I put 35ltrs in. immediately the fuel gauge dropped to empty and the fuel light came on. It is almost like the system is working in reverse??? Quote Link to comment Share on other sites More sharing options...
Tanuki Posted March 14, 2013 Share Posted March 14, 2013 Sounds to me like the resistor-track on the sender in the tank has failed. Basically, there's a float which moves an arm which moves a contact up and down a coil of resistance-wire in response to the different level of fuel in the tank. With time, and lots of fillings/emptyings of the tank (aided by the effects of fuel-sloshing in the tank as you go up/downhill and round corners) the moving contact wears through the resistance-wire coil. Once this happens your fuel-gauge becomes as trustworthy at indicating tank-fullness as Mystic Meg is at predicting next weekend's lottery-numbers. --Tanuki. "Badgers: always part of the problem, never part of the answer" Quote Link to comment Share on other sites More sharing options...
rovernut Posted March 14, 2013 Author Share Posted March 14, 2013 I would put it down to that if I hadn't changed the fuel pump before Christmas with a brand spanking new one. I have been out there for the last hour or so checking plugs and connections. I have now noticed that the fuel gauge reads zero (fuel light on) when the engine is running. If I leave the ignition on only, the gauge reads correctly once the fuel pump times out. Is it possible the fuel pump has a dodgy earth and is earthing through the sender coil. If so, does anyone know where the fuel pump picks up its earth at the front end ? As I have an inspection hatch cut into the load bed I suppose I could try running a separate earth to the pump and see what happens. Quote Link to comment Share on other sites More sharing options...
RedLineMike Posted March 14, 2013 Share Posted March 14, 2013 as a slight spin off, could you do me a slight favour & once you have sorted out the fuel guage not reading correct, can you stick a meter on it & have a look at what the resistance is when its full vs empty please? Quote Link to comment Share on other sites More sharing options...
rovernut Posted March 17, 2013 Author Share Posted March 17, 2013 Can't be sure I have cured the Gauge fault but found a major problem when the fuel pump was unplugged. The main earth pin on the pump itself was pushed through the top of the pump and no longer connected. This must have been slowly dropping out for ages. The main thing is, that if you don't break into the fuel lines, the Td5 must be able to run without the pump. I have noticed that she has been a bit lumpy on start up but I put that down to cold weather and I suppose, because I have only driven in heavy traffic to and from work, I hadn't noticed any significant loss of power. Until the araldite goes off and I can re connect the pump, I won't know if the gauge problem is related. Somehow I think it very likely. Quote Link to comment Share on other sites More sharing options...
rovernut Posted March 17, 2013 Author Share Posted March 17, 2013 FOOTNOTE: I have re-connected and it is so reasuring to hear the hum of the fuel pump. The gauge is working correctly and must have been trying to create an earth for the pump. RED LINE MIKE, sorry but I havn't removed the pump, so I am unable to get you the readings. However, I still have the old pump and will take the readings from that and post them when I can. Quote Link to comment Share on other sites More sharing options...
RedLineMike Posted March 17, 2013 Share Posted March 17, 2013 thank you (thumbs up) Quote Link to comment Share on other sites More sharing options...
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