Drumster Posted August 7, 2012 Share Posted August 7, 2012 The 7 got a real proper soaking on Sunday, on hill climb and then on trailer on way home, so I guess this could be water related? Moved car off trailer this afternoon and as soon as you switch on ignition 2 things happen: 1. The fuel gauge shoots all the way round the the right past full (no more than 10 litres in tank) and 2. The flasher relay is clicking at double speed as if there is a bulb out somewhere but neither indicators or hazards are switched on. When you switch hazards or indicators on they work as intended and flasher relay clicks at normal speed. Is anyone able to give me some pointers as to what to check. If an earthing point which one? Dodgy relay? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 7, 2012 Share Posted August 7, 2012 Does sound like water ingress - gauge going full scale is the same as grounding the cable on to the engine. Or it could be something has rubbed through the insulation of the cable across the top of the tank ? Flashers - maybe flasher unit falling out partially ? Water in the indicator or more likely - hazard switch ? Link to comment Share on other sites More sharing options...
Area Representative z7 Posted August 7, 2012 Area Representative Share Posted August 7, 2012 Given the proximity of the gauge and switch, I'd check the dash behind them to ensure it's dry and there's no trapped water. z7 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 16, 2012 Member Share Posted August 16, 2012 Was there a solution? Jonathan Link to comment Share on other sites More sharing options...
Drumster Posted August 16, 2012 Author Share Posted August 16, 2012 Finally today, yes. The relay problem has diasappeared so something somewhere got a right soaking AFAIK. The fuel gauge was an infuriating one. I cleaned the earth contact for the sender, tried it all out and it worked. Today, same old problem ☹️. Now this might be complete rubbish, but I think it had something to do with the fuel tank not earthing. When I put the new tank in, the ledge on which it sits has rubber strip attached as do the tank retaining straps to protect the tank, but somewhere there has been an earth. All I have done today is take an earth from one of the sender bolts on the tank and attach it to the same mounting point for the fuel gauge earth and this has solved the problem. Therefore I can only assume that during the hillclimb the tank had moved the smallest amount and lost it's earth. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 16, 2012 Member Share Posted August 16, 2012 Thanks Jonathan Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 16, 2012 Share Posted August 16, 2012 Earth sounds right - as the type of senders used tend to need an earth. I recall an earth cable connection on to one of the sender bolts I am sure. Link to comment Share on other sites More sharing options...
EFA Posted August 17, 2012 Share Posted August 17, 2012 Chris, The fuel tank does not need to be grounded, but the sender does. The wire with the ring terminal which connects to the sender body is connected only to the cars earth. The gauge gas 3 wires coming from it (if you ignore the bulb) these are: Signal from the sender +12v Ground/Earth I would suggest +12v has to be there as you get the full scale deflection. I think you have the signal from the sender present. The Ground/earth is what is missing, and it is this which by coincidence is close by the hazzard/flasher wiring. Now you need to borrow a decent digital multimeter. I have one, though I am sure there is probably someone closer.... If you pull the 3 way connector off the back of the gauge, you should be able to measure the +12v voltage on the GREEN wire, and you can check the resistance to battery -ve for the black wire, which should be less than 2 ohms. Then you can look at the resistance of the GREEN/BLACK TRACER wire which is the signal from the sender, and between that you should have a resistance which varies when you wobble the car and slosh the fuel around a bit. My money is on the BLACK wire being the issue. On cars of your vintage there are 4 places the loom grounds to chassis. These are (and I would clean and check them in this order): The wiper motor bracket, under the scuttle. The brake like switch on the chassis by the pedal box cover (nearest bellhousing) Inside the rear body on an offside rear wing bolt On the brake hose T near the front right suspension top wishbone (rear mount) Good luck. Reassure yourself its nothing expensive. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 17, 2012 Share Posted August 17, 2012 and this has solved the problemFrom Chris's last post above .... Link to comment Share on other sites More sharing options...
elie boone Posted August 17, 2012 Share Posted August 17, 2012 I know it's solved but just a note, if the gauge shows more than full the wire to the gauge is probably direct to the earth, so as your 7 was very wet, maybe there was water on the senderplate or your wet wooden boot floor was touching the gauge wire. Link to comment Share on other sites More sharing options...
Drumster Posted August 17, 2012 Author Share Posted August 17, 2012 Thanks Arnie, Elie Link to comment Share on other sites More sharing options...
elie boone Posted August 17, 2012 Share Posted August 17, 2012 😶🌫️ Link to comment Share on other sites More sharing options...
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