Joined: Mar 2018 Posts: 7 Threads: 3
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I was fortunate enough to buy back the 1933 RP Saloon I previously owned 40 years ago & we are now 3 years into a very major restoration. Unfortunately the fuel sender unit had stopped working. Speedograph Richfield kindly offered to have a look at it but they are unable to repair or replace it. I have no criticism of them whatsoever; they would not even charge me for the return postage/packing which they paid for.
However has anyone any suggestions as to how it might (????) be repaired or replaced please. I am not optimistic but as we are trying to do a concurs restoration it would be nice to have a working fuel gauge to go with the re chromed bezel & guage on a restored dashboard.
Many thanks for any suggestions.
Alan.
Joined: Aug 2017 Posts: 1,715 Threads: 47
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
It is a simple rheostat and although I have never done so they could probably be rewound fairly easily, however it would be even easier to simply get hold a working unit, one or our cherished suppliers could help there I am sure.
Black Art Enthusiast
Joined: Aug 2017 Posts: 148 Threads: 6
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I am not sure if the sender is voltage sensitive, but my Ruby (12 volt ) and the Pearl I am doing at the moment will be 12 volt also, on both I have used a pre 1974 Midget/ Sprite sender , you have to bend the arm down 1/2 inch and mount it so the float is to the right of the tank (from the front ) to avoid the float touching the baffles.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
One of the greater mysteries of life is why a sliding electrical contact in more or less direct communication with the vapours of a petrol tank does not initiate explosions. Apparently not even when contact erratic, wires broken etc. Perhaps someone can explain.
When tinkering some care is necessary nonetheless.
Joined: Aug 2017 Posts: 616 Threads: 19
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Location: Hampshire UK
As others have said, the sender is a simple variable resistor. A sliding contact moves in an arc over a thin rectangular insulating card wound with resistance wire. For the early sender type used in 6 volt Sevens (Smiths G33 system), the winding resistance is about 25 to 30 ohms, rather lower than many later types and modern replacements. Careful dismantling and inspection should reveal any electrical problems, and a cheap multimeter will come in useful. The mechanical parts should be checked for a pinholed float etc.
It's not immediately obvious that the resistance wire is earthed to the casing of the sender by trapping it between the casting and an insulating bush which carryies the "hot" connection through its centre. This earth connection can corrode over time, giving a poor or nil connection.
It's also not immediately obvious that the tank is (or was originally) insulated from the car by rubber dogbone washers, and the earth return from sender to battery is via the copper petrol pipe to the pump and thence to the engine block. Clearly, any plastic or rubber pipe sections in place of copper will break this connection.
Let us know how you get on - more advice available on request !
Joined: Aug 2017 Posts: 148 Threads: 6
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I am not sure if the sender is voltage sensitive, but my Ruby (12 volt ) and the Pearl I am doing at the moment will be 12 volt also, on both I have used a pre 1974 Midget/ Sprite sender , you have to bend the arm down 1/2 inch and mount it so the float is to the right of the tank (from the front ) to avoid the float touching the baffles.
Joined: Aug 2017 Posts: 148 Threads: 6
Reputation:
3
£24.99 from Auto Electrical Supplys
