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Fuel tank sender unit - 1947 Morgan 4/4

Any thoughts/opinions would be welcome re this problem, guys.

Fuel gauge didn't work; problem traced to tank sender unit, so new sender unit purchased - actually for 1966 A-H Sprite, because we knew it would physically fit (ring of 6 bolts). New one did work but, unfortunately, wrong way round: when tank was full gauge read empty and visa-versa.

The fuel gauge will not be a Morgan original, having been sourced at an autojumble. Important details are that: (1) with igniton off gauge reads empty and (2) with ignition on but sender unit wire disconnected gauge reads full.

So, presumably, we need a sender unit with the six hole round plate base which gives maximum electrical resistance when the tank is full of fuel, least resistance when empty. Please can anyone comment on this analysis and /or give advice on what sender unit might be appropriate and/or from where it might be purchased.

Thanks in advance,

Tony

Reply to
vat677
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So use the one you have, upside down and with the wire bent a bit if necessary.

Ian

Reply to
Ian Johnston

Smiths made a universal sender kit. There are others that do the same.

Reply to
Rob

Not necessarily so. There are two types of gauge, the one that flaps around when you go over a bump with a half full tank, and the one that stays steady. The one that flaps around is normally connected to directly to a live ignition circuit and reacts directly to the sender unit, like an ohmmeter would. The type that holds steady usually has a heater and bi-metal strip inside, and works off a stabilised 10 volt supply. Depending on which way the bi-metal strip is designed to bend when heated, increased heat can result in either a higher or lower reading. So it is possible for a gauge to be designed so that it reads full with the sender at minimum resistance, though whether your is, I can't say. What you need to do is put a meter on the sender unit you have bought and see which way round the resistance changes as you move from empty to full. Your gauge is expecting the opposite.

I am not familiar with your tank unit either, but is there any way of reversing the ends of the variable resistance electrically?

Jim

Reply to
Jim Warren

Just as a thought why not ask the Morgan Company if they can suggest a unit - the company seems to take an interest in all there cars old or new.

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Reply to
Rob

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