Fuel Sender Unit Revisited

[fattogatto]

Apologies for revisiting this subject but after searching I find no apparent easy solution. Original fuel level sending unit on 1967 British S3 is in pretty bad shape. From what I've read it may be best to send the whole thing off to Foreign Speedo Inc. in San Diego and let them rebuild if possible.

Does anyone have a better solution? What was the original source of the unit? It should have been something generic I assume. I do have the replacement ally tank.

Thanks,

[prezoom]

My unit had an open coil that they were able to repair. Still working after almost 10 years.

[fattogatto]

Thanks.

[weddingcarclive]

Have you opened it up ? it is only a finger type contact which glides over a winding of thin wire, only problems really are the wire has snapped giving an open circuit in which case rejoin it, finger contact has debri built up on it, clean it and entire length of wire winding with brake cleaner, and first thing to check is the float not having fuel leaked into it, thus stopping it from floating, they are very simple in how they work, also are you sure it is the tank unit that is faulty ? test by touching the wire that goes onto the spade of the tank unit to earth,(scraped clean chassis etc) if the gauge goes to full then the fault is in the tank unit and follow procedure above (remember to have ignition on whilst doing it).
If the gauge doesn't move then you have either a faulty gauge or wiring circuit fault, good luck and hope it saves you a few dollars

[sveris]

Rejoining the broken wire changes the resistance, even if you are very careful to use the very tiniest amount of solder. I've done it twice, and although you will end up with a unit that works, the reading on your gas gauge will not be the same as they were prior to the break.

Steve in Ohio

[john.p.clegg]

...as if they were ever that accurate...

John

[mbell]

If you need a new float I found that a Omix-Ada 17729.0 (Jeep CR 55-86) was a drop in almost identical replacement for the +2 sender float and expect it would also be for the Elan. These are cheap and easy to find in the US.

[yvesmontreal]

The Elan sender is a specific Smiths part, but very similar to other Smiths senders from the same period.

A complete TR6 sender from Moss can be easily modified to fit an Elan in less than an hour.

http://www.lotuselan.net/forums/lotus-carbs-f40/fuel-level-sender-substitute-t34391.html

Note: Smiths changed the resistance on its fuel gages sometime around 1967. This would fit a later car which has 230 ohms empty, and 0 full. Earlier cars had 90 ohms full and 0 empty. I believe earlier cars could use a TR3 sender modified in a similar manner.

[Certified Lotus]

Here is some info on what I ended up with:

lotus-carbs-f40/fuel-tank-sending-unit-t33947.html#p230280

Once I fixed the leak of the mounting bolt holes and had the fuel gauge modified to handle the different OHM load, it worked fine. Contact Ken at Dave Bean, he can get you all squared away!