Rowland Cook Posted May 31, 2011 Share Posted May 31, 2011 Question: Has anybody else had a hopelessly inaccurate fuel indication and if so, what did you do about it. My fuel gauge reads only three quarters full even when the tank is brimmed to the fuel filler, and rapidly falls to indicate empty even though the tank is still about one third full. This makes going on a long journey a bit of a leap of faith unless I stop at every petrol station on the way. I can count the miles in the odometer but the fuel consumption varies dramatically (HPC on carbs!) so a better indication would be preferable. The gauge is a Caerbont ACF1208-00 'Caterham 71163' with a Caterham logo. The sender has the number TB 1114/034 and is a standard float arm and resistor type. Over its travel it registers 23 to 235 ohms at 63 to 18 mA. I suspect that the gauge and the sender are not compatible. The float arm has been bent to a 'Z' shape to accommodate the confines of the tank and is not fouling at all. The above measurements were taken with the sender removed from the tank across its full range of travel. I'd be interested in what types of sender are fitted to other cars, if anyone has had similar experience and particularly if anyone knows a helpful fuel sender manufacturer who could possibly help. Thanks in advance, Regards Rowland Link to comment Share on other sites More sharing options...
john milner Posted May 31, 2011 Share Posted May 31, 2011 Can't help other than confirm you have a problem as mine says full when it is full and seems to be acceptably accurate. Full to red is 220-280 miles on a 160 VVC. Link to comment Share on other sites More sharing options...
JetSepter Posted May 31, 2011 Share Posted May 31, 2011 I had the opposite problem in my new RS 175 Duratec: it would read full for a long time before reluctantly dropping slowly towards the empty end of the gauge. I had Caterham look at it twice. I was assured it was OK (ie working) and told that the sender did not work in a linear fashion, and it was therefore a question of having it more accurate at either the top or bottom of the scale, and CC had preferred to set it for the latter. Having said that, even when I let it get below a quarter on the gauge, I have never managed to get more than 25 litres into the 41 litre SV tank. Have you got room to carry a green can with 5 litres in it to provide peace of mind on longer journeys, rather than having to stop at every garage you see? Link to comment Share on other sites More sharing options...
andy21 Posted May 31, 2011 Share Posted May 31, 2011 Slightly off topic - what should a Duratec r300 get from a tank.120 miles & It's generally below a quarter on the gauge. do they have smaller tanks on these? Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted June 1, 2011 Area Representative Share Posted June 1, 2011 As the owner of Crossflow car, I know how small a tank can feel! It's the accuracy at the bottom of the scale which is vital. From your description, I do think you have a fault, as mine behaves better. Link to comment Share on other sites More sharing options...
Mr Locust Posted June 1, 2011 Share Posted June 1, 2011 Have a look at the back of the gauge. Many of the Caerbont gauges are old Smiths designs which can be adjusted for accuracy at the lower and upper ranges. Look for two bungs in the back of the casing. Do they look like these? Link to comment Share on other sites More sharing options...
Adrian Williams Posted June 1, 2011 Share Posted June 1, 2011 Rowland I think you could be on the right track with the steps you've taken so far. I'm relying on my memory here but most HPC's on carbs would have been supplied with vdo fuel gauges which were standard fit when the HPC was launched circa 1991-92. The Caterham branded gauges were introduced circa 1995-96 by which time the majority of cars (of all types) would have been injection and hence used the 'injection fuel tank' complete with integral high pressure pump. I've no idea if the sender in both types of tank is the same or if the different types of gauge need different senders but I agree that you should start there. Hopefully someone can confirm either way. Adrian Link to comment Share on other sites More sharing options...
Rowland Cook Posted June 1, 2011 Author Share Posted June 1, 2011 Wow Thanks everybody. I've had the gauge out and unfortunately there are no adjustments on the back of it as per the pictures 'Mr Locust' posted. (Sigh!) I do carry a 5 litre can in the 'boot' but when I went touring Scotland I fund that the density of petrol stations dropped off rapidly after going North of Aberdeen particularly on the side roads. I also found that running dry had a tendency to pull a bit of dirt through to the carbs causing a lot of stuttering at idle and a float chamber strip and clean. I remember sitting at the side of Loch Earnhead up to my armpits in petrol muttering 'I'm going to fix this gauge or else sell the bl**dy car !!!!'. Thanks again keep the support coming ! Regards Rowland Link to comment Share on other sites More sharing options...
David Brown Posted June 2, 2011 Share Posted June 2, 2011 Does the float go right to the bottom of the tank or need bending down? David Link to comment Share on other sites More sharing options...
David Lynch Posted June 2, 2011 Share Posted June 2, 2011 Raceparts 250489 sender should be a Caerbont unit to match your gauge? Not sure if arm is modified in S3 tank Also photo here Link to comment Share on other sites More sharing options...
Rowland Cook Posted June 2, 2011 Author Share Posted June 2, 2011 Team Have checked the sender for correct movement across its whole travel and tried different orientations in the tank. That's not the problem. Have contacted a company called Technisol ltd who specialise in car instrumentation amongst other things and they have checked the gauge, which apparently is a Smiths specification not a standard VDO gauge. The sender is compatible with the gauge. They suggest that the gauge is faulty and I'll check it tomorrow and see what happens. Thanks for your help and advice. I'll let you know what happens. regards Rowland Link to comment Share on other sites More sharing options...
Rowland Cook Posted June 6, 2011 Author Share Posted June 6, 2011 Team Have checked the gauge and it is fine. Have checked the sender again and found very variable and jumpy readings for resistance. So ! cleaned the contacts on the sender (they were a little tarnished) - problem solved ! How easy it is to overlook the obvious! I shall now go and keep a low profile for a while. Regards Rowland Link to comment Share on other sites More sharing options...
Adrian Williams Posted June 7, 2011 Share Posted June 7, 2011 Thanks for the update Rowland Adrian Link to comment Share on other sites More sharing options...
elie boone Posted June 7, 2011 Share Posted June 7, 2011 And while you are working on the fuel system put a fuel filter in the system, saves you a clean of the float chambers Link to comment Share on other sites More sharing options...
Pezky Posted June 7, 2011 Share Posted June 7, 2011 Can't help other than confirm you have a problem as mine says full when it is full and seems to be acceptably accurate. Full to red is 220-280 miles on a 160 VVC. How on earth do you get 280 miles on a tank 🤔 Link to comment Share on other sites More sharing options...
Brian Soper Posted June 7, 2011 Share Posted June 7, 2011 My dip stick has never failed totaly acurate and I have only run out 3 times in 30 years !! once on Christmas day!!!! it ran ok on the 2 stroke mix a friendly gardener lent me! Link to comment Share on other sites More sharing options...
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