Fuel Tank Sender

[Rob Clarke]

Hi there,

 

I am restoring a 63 TR4, a complete nut and bolt job, and have got to the fuel tank and sender. All refurbished and ready to go back in, I just have a nagging concern about the sender that sits in the fuel tank. Both the original and a spare have no seal to the metal plate covering the rheostat workings. It follows that fuel and vapour can get inside the box where the electrical connections and rheostat are housed. Obviously modern replacement units will be sealed, but if these original units were ok in use, I am happy to leave it as the factory intended. I just wanted to check with experience from other members if there is supposed to be a seal and that they are just both missing from the units I have?

 

Any advice / opinion welcome.

 

Many thanks,

Rob

[RobH]

Nope - no seal necessary. It doesn't matter that fuel and vapour get into the sender mechanism (except that they can corrode the metals inside). AFAIK modern senders are not usually intentionally sealed either except in so far as the housing may be plastic and glued together for cheapness. It would be rather expensive to have a good enough seal to prevent any ingress.

Liquid petrol does not burn - only the vapour does and that has to be between about 1.5% and 7.5 % vapor-to-air ratio by volume. Ouside of that it will not ignite and you are not likely to get a ratio as low unless the tank is completely empty. Also the voltage is too low and the current limited, preventing an energetic spark, so ignition from that source is all but impossible.

[Rob Clarke]

I couldn't have asked for a more comprehensive answer.

 

Thank you Rob