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Car Forum / Land Rover Cars / March 2007Miscellaneous Fuel Tank Questions
Have installed a new fuel tank on SIII SWB this weekend. The one I removed wasn't exactly attached in quite as secure a manner as you might have hoped and was missing several (nearly all) securing bolts. From my Haynes manual, the three securing bolts to the rear of the tank appear to need some kind of 'spacer' so aren't just standard nuts and bolts. Can anyone let me know the correct specifications and whether these are specialist or can be obtained from local hardware store? The fuel gauge sender unit only had a single wire attached and as it had been functioning in some vague capacity I can only assume that it was earthed via the tank's attachment to the chasis. I am getting no fuel level reading at all now so presume I need to run a new earth from the other terminal on the sender unit back to the battery. Where would be a sensible (the proper?) place to attach this new earth into the wiring system? Peter  SignaturePosted via a free Usenet account from http://www.teranews.com > Have installed a new fuel tank on SIII SWB this weekend. The one I removed > wasn't exactly attached in quite as secure a manner as you might have hoped [quoted text clipped - 15 lines] > -- > Posted via a free Usenet account fromhttp://www.teranews.com There are some rubbers for the three fixings, the front is just a bolt. The earth wire usually just goes under a scerw on the tank - any good earth will do! Richard >Have installed a new fuel tank on SIII SWB this weekend. The one I removed >wasn't exactly attached in quite as secure a manner as you might have hoped [quoted text clipped - 3 lines] >correct specifications and whether these are specialist or can be obtained >from local hardware store? You can see the correct fixings here, from the parts manual http://www.cbmsys.co.uk/swbfueltank.pdf Front mounts are standard nuts/bolts the rear single bolt fixing is a bit special, but can be achieved simply with a rubber bush, a longer bolt and a bit of jiggery-pokery. >The fuel gauge sender unit only had a single wire attached and as it had >been functioning in some vague capacity I can only assume that it was >earthed via the tank's attachment to the chasis. I am getting no fuel level >reading at all now so presume I need to run a new earth from the other >terminal on the sender unit back to the battery. Where would be a sensible >(the proper?) place to attach this new earth into the wiring system? It does earth through the tank, if you suspect a failing earth then a wire under one of the screws holding the sender in, run this back to a good earth location, there should be a suitable earthing point on top of the bulkhead somewhere. It is possible the sender is iffy, they do get erattic. Alex > It is possible the sender is iffy, they do >get erattic. LR senders seem to have a special ability to work once you pull them out of the tank to test, yet they give up the minute they are screwed back in ;) I had the one on my 101 out of the tank and moved it by hand and watched the gauge move. back in the tank and it always says empty! >> It is possible the sender is iffy, they do >>get erattic. [quoted text clipped - 5 lines] >I had the one on my 101 out of the tank and moved it by hand and >watched the gauge move. back in the tank and it always says empty! From personal experience, I know that fuel tanks on 101's are *always* empty or nearly empty. Alex > From personal experience, I know that fuel tanks on 101's are *always* > empty or nearly empty. New tanks are available from our spares man though.... Steve >> From personal experience, I know that fuel tanks on 101's are *always* >> empty or nearly empty. > >New tanks are available from our spares man though.... Doesnt matter how new the tank is, the V8 still sucks the petrol out of it at a phenomenal rate. Alex >> It is possible the sender is iffy, they do >>get erattic. [quoted text clipped - 5 lines] > I had the one on my 101 out of the tank and moved it by hand and > watched the gauge move. back in the tank and it always says empty! Seen that a few times on these Lucas gauge senders (not on a LR yet) The wire 'arm' of the gauge sender is bent into a 'C' shape to hold the plastic float and over time the sharp end of the 'C' makes a tiny hole in the float. The clever bit is that the float fills completely with fuel and so looks empty even when it's full. On two occasions now I've managed to squeeze all the fuel out and repair the hole with a drop of epoxy resin - you can then fix the other end of the float to the arm. Next time I'm going to drill two large holes in the float and squirt expanding PU foam in one end and see if that works. I've not found a separate supply of floats yet, you have to buy a complete new sender. Julian. >>> It is possible the sender is iffy, they do >>>get erattic. [quoted text clipped - 18 lines] >expanding PU foam in one end and see if that works. I've not found a >separate supply of floats yet, you have to buy a complete new sender. hmmm. ill check for that! whenever i have had it out to test it the tank has actually been empty so i wouldnt be able to tell if the float was actually full >>>> It is possible the sender is iffy, they do >>>>get erattic. [quoted text clipped - 25 lines] > tank has actually been empty so i wouldnt be able to tell if the float > was actually full Whip it off the wire arm and 'bounce' it in the palm of your hand - you'll feel the weight of the thing then. I was astonished when I found the problem, I'd have never believed that the float could become completely full of petrol, and always assumed that a punctured float (same applies to carb floats) would be partially full and the petrol would slosh around when shaken. With the Lucas floats, the (initially) white translucent plastic become yellow and more opaque with age thus further hiding the fact that it's full of petrol. Julian. > >>>> It is possible the sender is iffy, they do > >>>>get erattic. [quoted text clipped - 37 lines] > > Julian. It's rather obvious by weight without removing it from the arm if it's full of fuel, but there's always a few second hand ones knocking about at your local car or Landrover breakers, I've got at least three. I would imagine that the OP's problem is a bad tank earth to the chassis, possibly with painting to protect the tank. Martin >It's rather obvious by weight without removing it from the arm if it's full >of fuel, but there's always a few second hand ones knocking about at your >local car or Landrover breakers, I've got at least three. I would imagine >that the OP's problem is a bad tank earth to the chassis, possibly with >painting to protect the tank. it wouldnt be obvious if the tank was drained and had been sat empty for a while - even if the float did fill up, when sat in an empty tank it would surely drain again. This is how my tank has always been so i should take it out next time whilst the tank has some juice in. > I would imagine > that the OP's problem is a bad tank earth to the chassis, possibly with > painting to protect the tank. > > Martin Indeed, that was my original thought. But having spent sometime last night with my test meter I can report that there is a reasonable earth from the -ive terminal of the sender without the need for a separate cable. The new piece of information I gleaned is that there is no apparent circuit between the +ive and -ive terminals of the sender. If the sender works (as I believe) as a variable resistor then I would have expected to be able to measure some resistance across the terminals. Either it is broken, greater than the 200k ohms my unit will measure or there is a school boy reason I cannot measure it in this way. A further point that doesn't look quite right. The voltage between the +ive cable to the sender and the bulkhead (which I assume is earthed somehow) cycles between 5v - 11v on an approx 5sec interval. Voltage across the battery terminals is a healthy 14v. Should this be telling me something. Many thanks to all for their contributions, Peter SignaturePosted via a free Usenet account from http://www.teranews.com > > I would imagine > > that the OP's problem is a bad tank earth to the chassis, possibly with [quoted text clipped - 12 lines] > than the 200k ohms my unit will measure or there is a school boy reason I > cannot measure it in this way. There isn't a -ve or +ve terminal on the tank sender unit and there will be no apparent circuit between them as (assuming it's a diesel) it will have a low fuel warning terminal which is a simple switch which connects a warning lamp (blue) on the dash with the sender body and then to earth through the tank as the float nears the bottom of it's travel (or around 1/4 tank of fuel), and another terminal which connects the gauge to earth through a rheostat to the sender body then to the tank and ultimately to earth on the chassis. If the fuel tank itself is not earthed to the chassis there will be no direct connection between these terminals unless the fuel tank is almost empty and you may not notice this as the fuel gauge will barely read anything as the resistance of the tank sender unit to the gauge is at it's highest when the fuel is at it's lowest and 1/4 of a tank and above this connection will be broken. Assuming you have got two leads at the sender then earth them in turn and you will get either the blue warning lamp lighting up or the fuel gauge rising to the top, albeit slowly. If the vehicle is a petrol model then disconnect and insulate the one that lights the low fuel lamp. To check the sender connect your ohmmeter across either terminal in turn and the sender body, one will show open circuit fron full to 1/4 tank and no resistance from 1/4 tank to empty and the other will show low resistance in the full tank position and probably around 300 ohms or so when in the empty position. Oh, and *earth* the tank! Hope that's clear. :-) Martin > A further point that doesn't look quite right. The voltage between the +ive > cable to the sender and the bulkhead (which I assume is earthed somehow) [quoted text clipped - 4 lines] > > Peter > <snip>...some very useful information ... </snip> Thank you. Good news is that I now have a new fuel tank, a correctly working sender / gauge and a 175% increase in my understanding of car electrics. Superb group full of excellent advice. Peter SignaturePosted via a free Usenet account from http://www.teranews.com >> <snip>...some very useful information ... </snip> > [quoted text clipped - 7 lines] > > Peter Unfortunately 175% of sod all is still sod all! SignatureIf Your specification is vague or imprecise, you'll likely get what you asked for not what you wanted! Do not say it cannot be done, rather what is needed for it to be done! > >> <snip>...some very useful information ... </snip> > > [quoted text clipped - 9 lines] > > Unfortunately 175% of sod all is still sod all! I suppose it could have been explained more clearly and simply but at least he can read and understand and has the ability to sort it, *and* appreciates the the help that is offered. Martin >>>> <snip>...some very useful information ... </snip> >>> [quoted text clipped - 15 lines] > > Martin Jest Joshing! SignatureIf Your specification is vague or imprecise, you'll likely get what you asked for not what you wanted! Do not say it cannot be done, rather what is needed for it to be done! |
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