chris956 Posted October 7, 2014 Share Posted October 7, 2014 As per title really. My fuel gauge shows totally empty but still has over 10 litres left within and just wondered if there was a "5 minute job" to rectify ??? Link to comment Share on other sites More sharing options...
SM25T Posted October 7, 2014 Share Posted October 7, 2014 Remove the sender in the fuel tank and bend the float arm. Case of trial and error. Link to comment Share on other sites More sharing options...
mic Posted October 7, 2014 Share Posted October 7, 2014 Are you sure you can use all of the 10 litres, it depends which engine you have. Link to comment Share on other sites More sharing options...
chris956 Posted October 7, 2014 Author Share Posted October 7, 2014 Cheers SM25T , I`ll give that a go next time it reads rock bottom. @mic - I dont know is the answer as I have never driven it to dry. Once the needle on the gauge reaches absolute zero and then driven 10 miles I have drained the tank and gotten 10 litres out which means my fuel gauge is very very pessimistic. Mine is a Duratec R400Without taking it apart I have no idea if the feed pipe sits at the bottom of the tank or there is a small gap. If it is at the bottom then I can see no reason why it would not use all the petrol in the tank ( not taking into account cornering forces and surge ) Link to comment Share on other sites More sharing options...
SM25T Posted October 7, 2014 Share Posted October 7, 2014 I understand most cars have 5 litres unusable below the pick up. Link to comment Share on other sites More sharing options...
Mark w Posted October 8, 2014 Share Posted October 8, 2014 My car is at Caterham at the moment for some warranty items , this issue is one of them .Will let you know if they manage to sort it . Out of interest , when your gauge is showing empty how much fuel does it take to brim the tank ? I assume it's a standard car not an SV ? Link to comment Share on other sites More sharing options...
6speedmanual Posted October 8, 2014 Share Posted October 8, 2014 10l at reading "empty" as in "refuel now" is a hell of an error on a 35 litre tank! I too would support the idea to adjust the float, even it it means it lags on coming off "Full". It's less interesting at F. Make sure ignition is off when removing sender! Peter Link to comment Share on other sites More sharing options...
chris956 Posted October 8, 2014 Author Share Posted October 8, 2014 When initially hitting empty and first getting the car I found that it wouldn't accept more than 20 or so litres. I then ignored the empty needle and got brave but still can't get more than high 20's in it. Mine is an SV and I have been told its a 42 litre tank. Tomorrow is the day for sender out and some investigation. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted October 9, 2014 Share Posted October 9, 2014 On my R400D I put a 1000ohm and 2000ohm resistor in parallel with the fuel gauge wires from the sender (giving 667ohms of parallel resistance to the sender unit). With this value the gauge gives both a slightly better indication of full and is on zero with 7 litres in the tank (which seems to be about the minimum to avoid fuel starvation at the track). Due to the sloping bottom of the tank, a completely different float position and design would be needed to get the gauge to read zero when fuel in the tank is also zero. Link to comment Share on other sites More sharing options...
john aston Posted October 9, 2014 Share Posted October 9, 2014 I have a Stack gauge on R400D. I have never got more than 29litres in allegedly 35 litre tank. LIght comes on with 5 litre left. So I do have 35 litres but the last 5 litres can't be picked up ? Or something ? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 9, 2014 Member Share Posted October 9, 2014 On my R400D I put a 1000ohm and 2000ohm resistor in parallel with the fuel gauge wires from the sender (giving 667ohms of parallel resistance to the sender unit). With this value the gauge gives both a slightly better indication of full and is on zero with 7 litres in the tank (which seems to be about the minimum to avoid fuel starvation at the track). Due to the sloping bottom of the tank, a completely different float position and design would be needed to get the gauge to read zero when fuel in the tank is also zero. This sounds like the best approach to me.Would people be interested in a general-purpose circuit that allowed recalibrating the gauge display? I think someone has already published the resistance-level map. I suppose there may be more than one type of map.I'm surprised that more people who aren't happy haven't done the following:1 Empty tank.2 Mark gauge with a Letraset line or similar.3 Add 5 litre of fuel.4 Mark gauge.5 And so on until full.6 See if using those marks works out better in practice.Jonathan Link to comment Share on other sites More sharing options...
chris956 Posted October 9, 2014 Author Share Posted October 9, 2014 That sounds about right. Link to comment Share on other sites More sharing options...
AndyD Posted October 10, 2014 Share Posted October 10, 2014 I'd be interested in a circuit to do the job, Jonathan. Link to comment Share on other sites More sharing options...
chris956 Posted October 12, 2014 Author Share Posted October 12, 2014 Hit a snag trying to take it all apart today. There is a pipe connection ontop of the sender unit. Black plastic with no obvious way to undo it. It is the fuel pipe connection and I`ve tried giving it a yank but dont want to break it.It looks like there is a small hole to insert a tiny flay head screwdriver so I did that and gave it a wiggle but still no joy. Anyone know the technique or "nack" ??? Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted October 26, 2014 Share Posted October 26, 2014 There is a special Ford tool to remove that connector (and also another for the fuel pump to fuel tank clamp ring), but if you Google "ford fuel pipe removal tool", there are videos of various techniques that have been used to do that. Link to comment Share on other sites More sharing options...
ChrisC Posted October 26, 2014 Share Posted October 26, 2014 Maybe I am a bit late to this thread, but surley the most important part of a fuel gauge to calibrate is the empty point, to do this just drive carry a 5lt backup can of fuel, and drive until its empty, and where ever the fuel gauge is, thats where is will be when the tank is empty. Way cheaper than breaking the fuel pump / sender monster in the tank have you seen it price? Link to comment Share on other sites More sharing options...
chris956 Posted October 26, 2014 Author Share Posted October 26, 2014 Is looking like the easiest option Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 26, 2014 Member Share Posted October 26, 2014 As post numbers have appeared... as in Post #11? ;-) Jonathan Link to comment Share on other sites More sharing options...
RedCat7 Posted June 12, 2015 Share Posted June 12, 2015 Aerobod's solution has worked a treat on my Sigma SV. That is putting a 1000ohm and 2000ohm resistor in parallel with the fuel gauge wires from the sender (giving 667ohms of parallel resistance to the sender unit). Previousely, the gauge was very pessimitic - on the red after 150 miles. Now I think it will hit the red at about 250 miles (I last filled up after 215) which is spot on. Many thanks Aerobod! Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted June 13, 2015 Share Posted June 13, 2015 Glad to be of help! Link to comment Share on other sites More sharing options...
Nigel Riches Posted June 13, 2015 Share Posted June 13, 2015 My cranky old 7 with Smiths gauges reads "E" from about 150 miles, and I believe this, as a couple of years back at 215 miles it spluttered to a stop, giving me a 3km walk to get a recharge. Which type of fuel gauge do you have? The old ones such as I have vary with voltage and duration of operation, as they are a thermal type indicator, notoriously unreliable display in the short term, not so bad over a longer period.The parallel resistor trick would be worth a try, and also drain tank, to the point where the engine won't run, add 10 litres and calibrate the gauge accordingly. There should always be a volume of ullage, so that any contamination remains below the supply port, this may well be 5 litres, given the size and shape of the tank. Nigel. Link to comment Share on other sites More sharing options...
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