JeffR Posted July 16, 2010 Share Posted July 16, 2010 A question (or two) for the collective mind. replaced the fuel tank and pump on my 110V8 earlier this year. Prior to change, the low fuel warning light was always slow to react, but did actually work, as did the fuel gauge. When transferring the sender over I cleaned the terminal back to metal. Every thing worked, then the devil got involved. Now nothing works (other than the low fuel light never goes out)- ever tried living with a V8 when you've absolutely no idea how much petrol is in it, rather play russian roulette with a Glock. Went back to first principles - first thought was cattle trucked sender unit, took out said unit, checked that resistance changes when float was moved and it did. Not sender unit then, replaced it with a new one anyway. Same with gauge - can get full deflection if put power across, also tried another gauge,still no joy. Removes tank (again!!) and attacks wiring - continuity tester says wiring fine where it comes out of chassis to rear loom (and if bit of wire added all is fine from gauge to sender). Added extra earth to sender unit, replaced RISTS connector with one that is splash proof - even cleaned wires back to shiney copper (earths and supplies) still no working fuel gauge. Am I missing something?, I've run out of things to try (and to replace). I give in, is the bloddy thing merely possessed or does it want me to kill it with a big stick - come to the conclusion that Landrover are living, sentient, though not necessarily inteligent, organisms. And this one don't like me. So in a nutshell HELP!!!!! Quote Link to comment Share on other sites More sharing options...
western Posted July 16, 2010 Share Posted July 16, 2010 are the sender wires back in the original terminal positions, if these are wrong the low fuel light will stay on. Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 16, 2010 Author Share Posted July 16, 2010 are the sender wires back in the original terminal positions, if these are wrong the low fuel light will stay on. Sadly yes! Also if one unplus everthing the wretched low fuel lamp merrily shines brightly!!! Quote Link to comment Share on other sites More sharing options...
western Posted July 16, 2010 Share Posted July 16, 2010 then it's getting a power feed from elsewhere or the warning light panel printed circuit has a incorrect connection. Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 16, 2010 Author Share Posted July 16, 2010 then it's getting a power feed from elsewhere or the warning light panel printed circuit has a incorrect connection. Thanks chaps - guess I'm just going to dismantle the dash again to see what I can find, gonna be a fun weekend! Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 17, 2010 Author Share Posted July 17, 2010 The plot thickens, but still no functional fuel gauge. Now got 12.5 volts input (engine off) to the fuel gauge and 7.5 volts at the sender unit. Re-earthed the sender unit directly to -ve terminal of the battery so no earth problem. Low fuel light still on, but as it must be getting low on fuel by now, it is probably telling the truth. I am assuming that the low fuel light works by sensing the variable resistance in the sender unit, or am I wrong in my assumption? This is driving me absolutely nuts - all the components seem fine until they are attached to each other. Or is it that I have missed something? Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 17, 2010 Share Posted July 17, 2010 The plot thickens, but still no functional fuel gauge. Now got 12.5 volts input (engine off) to the fuel gauge and 7.5 volts at the sender unit. Re-earthed the sender unit directly to -ve terminal of the battery so no earth problem. Low fuel light still on, but as it must be getting low on fuel by now, it is probably telling the truth. I am assuming that the low fuel light works by sensing the variable resistance in the sender unit, or am I wrong in my assumption? This is driving me absolutely nuts - all the components seem fine until they are attached to each other. Or is it that I have missed something? OK, breathe ... The fuel gauge and associated lamps etc. have two seperate circuits. The low fuel lamp is fed from the ignition (behind the instruments, white wire) and then a white / slate wire goes from the other side of the bulb to the sender unit. The bulb will only come on if you earth the white / slate wire somewhere. There is a seperate copper sector in the sender unit that does this when the level falls too low. The second circuit is the fuel gauge, which is fed by a green wire (behind the instruments) and the other connection goes via a green / black wire to another terminal on the sender unit. The higher the resistance of the sender unit the lower the gauge reads. Both circuits then go to earth via the other (black) wire. EDIT: Try unplugging the green / black and white / slate wires form the tank, turning the ign on and touching each one to ground in turn - the low fuel lamp should flash on and off and the fuel gauge should go to full and back respectively. EDIT2: You have checked to make sure the sender arm has a float on it and that this float can go up and down, haven't you?? Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 17, 2010 Author Share Posted July 17, 2010 OK, breathe ... The fuel gauge and associated lamps etc. have two seperate circuits. The low fuel lamp is fed from the ignition (behind the instruments, white wire) and then a white / slate wire goes from the other side of the bulb to the sender unit. The bulb will only come on if you earth the white / slate wire somewhere. There is a seperate copper sector in the sender unit that does this when the level falls too low. The second circuit is the fuel gauge, which is fed by a green wire (behind the instruments) and the other connection goes via a green / black wire to another terminal on the sender unit. The higher the resistance of the sender unit the lower the gauge reads. Both circuits then go to earth via the other (black) wire. EDIT: Try unplugging the green / black and white / slate wires form the tank, turning the ign on and touching each one to ground in turn - the low fuel lamp should flash on and off and the fuel gauge should go to full and back respectively. EDIT2: You have checked to make sure the sender arm has a float on it and that this float can go up and down, haven't you?? Been there done that! If you short out the gb and ws wires with the ignition on you get full deflection on the gauge and the low fuel light goes off. There is definitley a float on the sender unit, when the tank was replaced I also replaced the fuel pump but managed to trap the float down as the filter on the end of the pump was 90 degrees out. Suprisingly if you take the sender unit out (guess what I've been doing this afternoon) and attach the wires the gauge works, manually moving the float up and down results in the needle moving up and down!!!!!. The only time it doesn't work is when the wretched thing is in the f$%£"*%g tank. I am now thoroughly convinced that this bloody thing hates me with a passion - it's getting personal. Mind you I did fix the heated rear window today and removed about 30 foot of 50amp cable that wasn't attached to anything other than a switch! The previous owner of this vehicle was not the worlds greatest auto electrician!!!!! Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 18, 2010 Share Posted July 18, 2010 If you short out the gb and ws wires with the ignition on you get full deflection on the gauge and the low fuel light goes off. Eh? you short the WS wire to 0v at the tank end and the LF light GOES OUT? That's wrong then! I am now thoroughly convinced that this bloody thing hates me with a passion - it's getting personal. Mind you I did fix the heated rear window today and removed about 30 foot of 50amp cable that wasn't attached to anything other than a switch! The previous owner of this vehicle was not the worlds greatest auto electrician!!!!! I think we might be vectoring in on the problem here. I think the wiring is wrong at the dash end. Whip the instrument panel off and see what's what (piccies are good). Quote Link to comment Share on other sites More sharing options...
western Posted July 18, 2010 Share Posted July 18, 2010 the white/slate [WS] for the low fuel light should go direct from the tank sender to the warning light panel [not via the gauge] the warning light panel plugs cannot be fitted incorrectly as they are keyed to the actual light panel. on the warning light panel, the WS wire needs to be fitted to the right hand multiplug in slot 4 from the right hand end of that plug. still got my old warning light panel here for reference. Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 18, 2010 Author Share Posted July 18, 2010 Sorry I was having a blonde moment. I've been trying to sort this out for too long and getting very frustrated. If you bridge the two wires that go to the sender unit the gauge needle moves to full and the low fuel light goes out - a function that would suggest to me that the wiring to the gauge is fine , after all it is merely simulating a full tank. The dash wiring is as per the book,now that umpteen metres of assorted cable have been removed (must admit to putting a spare fuel gauge in the water temp hole - that caused some confusion) Beginning to think that the sender unit is cattle trucked (even though it is new), will try yet another one next week. Quite frankly I am about up to my t£$s with the wiring on this thing. Earlier this month I thought I would fit a set of NAS lights I had kicking around, should of taken about half a day, took 3 days and a complete re-wire. But I did cure the very slow flash rate of the side repeaters - some half wit had re-wired them using 50 amp cable of assorted colors and clearly couldn't be bothered to use bullet connectors when twisting the wires together was quicker, would have been nice if they'd wrapped the twisted ends in insulating tape though. They also created an ignition controled live feed for the radio by tapping into the brake light cicuit, again who needs to insulate a soldered joint (makes a change from twisting the wires together though) definitely a blue smoke, brown trouser moment. That one resulted in a melted fuse, after all we all know that if a fuse blows one replaces it with a chunk of copper wire. To top it all the they had forced imperial thread screws into the metric thread captive nuts that hold the fuse/relay housing to the bulkhead, and they used stainless screws - still got that to sort out. Have rivnut gun- the best tool in the world. Cheers folks will let you know if a new sender unit works, actually if it don't the cloud of oily black smoke that will appear over Haltwhistle is me setting fire to the tw£t.... Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 18, 2010 Author Share Posted July 18, 2010 Just out of interest, what the hell is the third (bottom) terminal for on a 110 Sender unit? Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 18, 2010 Share Posted July 18, 2010 Just out of interest, what the hell is the third (bottom) terminal for on a 110 Sender unit? An earth wire Quote Link to comment Share on other sites More sharing options...
western Posted July 18, 2010 Share Posted July 18, 2010 Just out of interest, what the hell is the third (bottom) terminal for on a 110 Sender unit? it's a ridged stud, for the tank unit earth. Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 21, 2010 Author Share Posted July 21, 2010 Well the new sender unit arrived today. 10 minutes of bad language later and it's in and wired up. Turns ignition on and guess what. It don't f"£$%&g work. Nothing no needle monvement what so ever, blood pressure reaches new all time high, hammer and drift fly majestically into the shrubbery.Squaddies blush at the frequency, amplitude and range of bad language. Gets gallon of petrol, check that box of matches works(the way my luck is going I'd have a bought a box of non flammable matches), rings fire brigade to let them know that the soon to be occurring conflagration is deliberate, wife and small children exit stage left. Wife suggests that we take the bloody thing out again and put it back in "give it one more chance", she says.Half an hour spent So out the bloody thing comes, youngest son hands me sender unit, back in it goes........ Turn ignition on and EUREKA needle moves and low fuel light goes out IT LIVES!!!! Then youngest son says "what you gonna do with the new one daddy?". He'd given me the old unit. The bloody old unit has had a Lazarus moment; in the words of Mr.V.Meldrew, I DON'T BELIEVE IT. So in the interests of my sanity I put the new one in and that works too. Heads to local filling staion, puts petrol in and the gauge appears to be telling the truth. The most annoying thing is that I still do not know just what the hell was wrong, that's a month of my life I will never get back, never mind got lots of new wiring in place, all earhts are cleaned up amd most things seem to work only got to sort out a leaking steering box, ditto swivel hub, put new back door on, put new door seals in, replace buggered heater matrix, replace second row sates with nice Trakers reclining jobbies, rebuild battery box and get gas conversion checked out, not a lot really..... Quote Link to comment Share on other sites More sharing options...
errol209 Posted July 21, 2010 Share Posted July 21, 2010 Turn ignition on and EUREKA needle moves and low fuel light goes out IT LIVES!!!! Err, congratulations? I wish this could have been easier, but glad it's sorted. Thankfully most of the other jobs you mention don't have wiring Quote Link to comment Share on other sites More sharing options...
western Posted July 21, 2010 Share Posted July 21, 2010 Glad it's sorted, keep the other sender, don't chuck it. Quote Link to comment Share on other sites More sharing options...
Gromit Posted July 21, 2010 Share Posted July 21, 2010 Thankfully most of the other jobs you mention don't have wiring Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 23, 2010 Author Share Posted July 23, 2010 Just waited an hour and a half for a very nice man from the AA to find me with a gallon of petrol!!! Both f£$%^&*g sender units tell more lies than a politician. Half tank of petrol indicated actually means you are running on the petrol that is in the carb float chambers. Sod it, this weekend the bloody tank is coming out its a Britpart unit - hopefully it's just the float catching on one of the internal baffles. At least with the tank and fuel pump pulled I should be able to see through the pump aperture just where it's catching. Watch this space........ Quote Link to comment Share on other sites More sharing options...
western Posted July 23, 2010 Share Posted July 23, 2010 oh heck, thought this was cured, will be watching closely Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 23, 2010 Author Share Posted July 23, 2010 So did I Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 26, 2010 Author Share Posted July 26, 2010 Had the bloody tank out again over the weekend (now takes less than 10 mins to drop the tank). Float arm is hanging up on an internal baffle. Mind you had to borrow a bore scope to work this out as you cannot see the baffles properly from the fuel pump aperture and short of drilling a bloody great hole in the sender unit..... Now all I need is a 2 foot long hacksaw blade that I can shove through the sender hole to create a bigger slot for the float arm. Might do that later on in the week. To top it all the wretched beast decidded to die on me half way across the A69 today (smell it madam, I was sitting in it!) - easy fix, it was the petrol cut off switch on the gas conversion having a hissy fit, now completly bypassed. Thank God I don't use the gas system - just out of interest can anyone recomend an autogas installer in Northumberland who can give the gas system a once over?? Quote Link to comment Share on other sites More sharing options...
western Posted July 26, 2010 Share Posted July 26, 2010 Good to hear you found the problem with the sender & have a fix for it. Quote Link to comment Share on other sites More sharing options...
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