| Author | Message | ||
     Randy Roberson Grand Master Username: wascator Post Number: 375 Registered: 5-2009 |
Ha! I thought I'd made the world's fastest correction of an inoperable fuel gauge: after removing the carpeted panel covering the fuel tank, I found one of the two spade connectors-not connected. Alas! connecting it made no difference to gauge operation; even loosening and tightening the ground made no difference. The gauge needle hovers near but not quite at "empty". The oil level system works great, though. I did find seven new Crewe-Bentley spin-on oil filters in their sealed boxes, in the storage compartment where the tank was in earlier models. I converted SRH 9391 to the spin-on filter last winter, but I will still have enough filters "for the duration", it seems. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 688 Registered: 5-2012 |
Hi Randy I had a similar problem. turned out to be a sunken float. If your faulty gauge is due to the same reason,a direct replacement for the fuel tank sender unit float is W0133-1634009. Available from http://www.partsgeek.com/7jh1r5n-jag...vel-float.html. My car is a 1974 Silver Shadow. I am not sure if this part applies to the series II, however a quick look at the photograph of the part should determine whether it is applicable. The diameter of the recess on the float where the clip fits is 1.00 inch.  Geoff | ||
| bob uk Unregistered guest Posted From: 188.29.164.172 |
Earth the wire and the gauge should go hard over to full. (Message approved by david_gore) | ||
| Randy Roberson Grand Master Username: wascator Post Number: 378 Registered: 5-2009 |
Great Suggestion bob uk, I will try this. Meanwhile I will have to get almost a full tank out to open up the sender and see if the float is sunk. | ||
| bob uk Unregistered guest Posted From: 188.29.164.184 |
To test tank unit remove from tank and move float by hand and watch the fuel gauge though rear window. Fortunately due to proper design this can be done without draining the tank on my 1974 car. (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: 94.197.121.239 |
The sender in the tank has a arm that sweeps a coil wrapped around a flat bit of circuit board. The coil and arm cause voltage and current to change thus operating the fuel gauge which is a voltmeter with empty full written on it instead of volts. The system voltage varies from 11.5v to 14.5v. By virtue of the alternator. A voltage stabiliser is fitted to the supply side. About 9 volts. Other wise as the revs go up and down the gauge would rise and fall. The stabiliser takes time to settle which is why on brit lucas systems the gauges dont flick when ignition is switched on. Also water temp gauge works the same way. Note some more modern but traditional looking gauges have a built in stabiliser. Should this type of gauge be used the original stabiliser should be bypassed. Sometimes a break occurs this can be repaired by un windind a turn and joining on the back of the board. This gives a jump in the area of the repair. But as long as the guage works at full and empty and a bit in the middle with reasonable accuracy then along with the low fuel light and milometer then you should be OK. The float is standard lucas and can be found on any brit car so equipped up to about the Austin Metro. So easy diy at little cost. I have repaired a few using this method. Or of course one can let some moths out of the wallet and by new. I run lpg only. When refueling I always fill to brim. Only 72 litres of lpg fits due to expansion ullage necessary im a 90 litre lpg tank. When I was running petrol ( horrid nasty stuff) I would drive until low fuel light came on and go to nearest petrol shop and stick £30 worth of go go juice in. I found my low fuel light reliable and besides the fuel needle when on empty meant 10 miles left. And I log mileage for insurance purposes, not that they seem interested. I mamaged to run the lpg out 1 mile from the pit stop due to very heavy traffic. The AA took the car to the lpg pump I filled it up with lpg while the car was still on the recovery truck. The car started so we unloaded it and treated our selves to tea and medals. Back to the sender. When removing the unit use a pair of water pump pliers to catch two of the tabs on the locking ring. When refitting use a spot of engine oil on the locking ring so it slides nice. Note the voltage stabilizer is about 1 inch square and 1/2 inch deep silver in colour with a small adjuster with a blob of glue on it. Do not adjust. They are not expensive. Standard Joe Lucas bit. (Message approved by david_gore) | ||
| Randy Roberson Grand Master Username: wascator Post Number: 379 Registered: 5-2009 |
Great advice, and enjoyed learning about the voltage stabilizer. I have noticed a couple of times now: the temp gauge is usually steady-on on the lower side of normal, but I caught it dropping suddenly to cold, then soon right back to normal. Today I saw the oil pressure gauge do this once: egad, montressor! but it wasn't actually the oil pressure, only a gauge glitch. I thinking bad ground. | ||
| bob uk Unregistered guest Posted From: 92.40.248.104 |
Also. I never accept car gauges as definitive. Always check before falling upon the engine with a box of spanners only to find after taking the engine out of a XJ6 to find the low oil pressure is caused by a dodgy gauge sender. Typical jag fault. (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: 92.40.248.104 |
Randy thankyou for enjoying my explaination of gauges and how they work. This is a good example of how to view a complicated machine in easy to understamd bits. My aim is to show how simple a RR is. When I first started on cars something like a Morrid minor looked complex and a RR was way beyond a Minor. As the years rolled by of fixing cars now a Minor looks to me a cake walk. A RR now looks like a well made Minor with more cylinders and accessories. From a fix it point of view. The LWB SY cars have a useful extra 4 inches to polish. 😃 The stretch is not obvious and a LWB car was taken into consideration in the original design. I find my back seat good for cat naps. (Message approved by david_gore) |
