bishbosh Posted October 12, 2006 Share Posted October 12, 2006 I am planning on repalcing the fuel tank in the Bishtail with a custom affair and will need a fuel sender that is compatible with the existing gauge. The original sender is a float arm type and gives 20 Ohms when full and 270 when empty.Well, that's what my cheapo multilmeter gives and consistently too. I will need a "sliding type" rather than the arm type due to the shape of the new tank. Looking around the web I have found these folk HERE who could on the face of it make me a custom sender for around £60. Is this a fair rate? Anyone know of alternatives? Also, is the low fuel light on the dash activated by the position of the gauge needle or some clever electrickery that I'll have to mimic? Cheers, Quote Link to comment Share on other sites More sharing options...
MogLite Posted October 13, 2006 Share Posted October 13, 2006 Bish Here are all the fuel gauge senders eGauges in the states do A 240-33 Ohm would probably be okay but by the time you've sourced one locally or imported, you might as well go for the £60 one Alternatives ....sight gauge....dispstick....fill up at every fuel station you see.....on-board jerry can....RAC card.....measure range....blind faith, the possibilites are endless Quote Link to comment Share on other sites More sharing options...
rtbarton Posted October 13, 2006 Share Posted October 13, 2006 Also, is the low fuel light on the dash activated by the position of the gauge needle or some clever electrickery that I'll have to mimic?Cheers, Could be either, older vehicles have a switch in the sender, these usually have two connectors on the unit, rehostat and switch. There may be a third for the earth, but some 'gauge only' senders may have two connectors, output and earth, although older ones tend to be earthed through the fixings. Modern vehicles have a circuit in the instrument panel which senses the voltage from the sender and illuminates a light when the level in the tank gets low. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted October 13, 2006 Share Posted October 13, 2006 Why will the existing sender not be suitable Bish? If it is merely the depth of the tank that will change then you could easily shorten or extend the arm on the existing sender. Chris Quote Link to comment Share on other sites More sharing options...
bishbosh Posted October 13, 2006 Author Share Posted October 13, 2006 Hmm, thinking about it, the sender has on ly two wires coming from it so the low fuel light must be dash controlled. Chris, I could try and make the existing one fit , but actually attaching it to the new tank would be a pain as it is integral with the feed and return lines. I could chop it up to liberate the sender part only but I'll still need a grown up to attach it to the new tank.... Andy, your alternatives are all very interesting. Would you like to try suggesting them to my wife who uses the Rangie daily.... . Was nice knowing you! Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted October 13, 2006 Share Posted October 13, 2006 Bish - it's not a V8 any more, you don't need a fuel gauge. Just set a reminder in your phone for a memorable date (the wife's birthday?) and brim it then. Quote Link to comment Share on other sites More sharing options...
western Posted October 13, 2006 Share Posted October 13, 2006 Bishy --- Also, is the low fuel light on the dash activated by the position of the gauge needle or some clever electrickery that I'll have to mimic? Some senders have 3 connections for earth/power/low level warning, in this case as on my 110, there is a relay behind the instrument pack that operates the low level circuit, I can't add any drawimgs at the moment as I'm far away from home, have a look at the circuit diagram here Quote Link to comment Share on other sites More sharing options...
rtbarton Posted October 13, 2006 Share Posted October 13, 2006 Hmm, thinking about it, the sender has on ly two wires coming from it so the low fuel light must be dash controlled. Not necessarily, if it's earthed through the mounting screws it will have an internal switch. The easiest way is to test it with an ohmmeter. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted October 13, 2006 Author Share Posted October 13, 2006 The multiplug has three wires. It feeds the pump and sender. There is a live and earth and one for the sender resistance. (See how technical I can be with electrickery! ) What I did notice was that the resistance change was not linear across the movement range of the arm. The face of the variable resistor also had a fancy saw tooth arrangement with the teeth increasing in size towards the full end. From 20 Ohms at full it only rose to about 50 at mid range before accelerating rapidly towards empty. I suppose this will be reflected in the way the gauge behaves? I liken it to the "bigger first half" of the tank scenario. Am I on the right lines? Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 13, 2006 Share Posted October 13, 2006 Am I on the right lines? I haven't a clue Bish old boy but it sounded good to me Mo Quote Link to comment Share on other sites More sharing options...
rtbarton Posted October 13, 2006 Share Posted October 13, 2006 What I did notice was that the resistance change was not linear across the movement range of the arm. The face of the variable resistor also had a fancy saw tooth arrangement with the teeth increasing in size towards the full end. From 20 Ohms at full it only rose to about 50 at mid range before accelerating rapidly towards empty. I suppose this will be reflected in the way the gauge behaves? I liken it to the "bigger first half" of the tank scenario.Am I on the right lines? Probably because the float arm describes an arc as the float rises and falls, but the amount of fuel is represented by the vertical (linear) motion of the fuel. I wonder if the resistance of the resistance path is a sine function of its length? Who knows? Who cares? Also if you have an odd shaped tank the shape of the resistance could be designed to reflect the true contents of the tank represented by the height of the float. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted October 13, 2006 Author Share Posted October 13, 2006 Probably because the float arm describes an arc as the float rises and falls, but the amount of fuel is represented by the vertical (linear) motion of the fuel.. Ah, thanks RT for pointing that out.Makes total sense. Now to find a sender for less than £75 delivered . Quote Link to comment Share on other sites More sharing options...
RocKeR Posted October 13, 2006 Share Posted October 13, 2006 I could try and make the existing one fit , but actually attaching it to the new tank would be a pain as it is integral with the feed and return lines. I could chop it up to liberate the sender part only but I'll still need a grown up to attach it to the new tank.... Not a removable one like mine then? Quote Link to comment Share on other sites More sharing options...
bishbosh Posted October 13, 2006 Author Share Posted October 13, 2006 Graham, That is exactly what I have now - the original RR pump and sender combo. The shape of my new tank will preclude the use of it though. I think I will try and butcher the old one to liberate the sender mechanism and then bond it to some plate that I can screw to the top of the tank. If it doens't work I'll go for the custom sender but that's £75 I could spend elsewhere on toys! Quote Link to comment Share on other sites More sharing options...
GBMUD Posted October 13, 2006 Share Posted October 13, 2006 Just cut the pump off the existing module, fit the sender and fit a seperate FI pump. Chris Quote Link to comment Share on other sites More sharing options...
Mark90 Posted October 13, 2006 Share Posted October 13, 2006 I've got a 2' length of garden cane you can have for a very reasonable price, and if you tell me the height of the tank I will even mark it it F-1/2-E for you Quote Link to comment Share on other sites More sharing options...
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