fuel sender

[mister bridger]

Fuel gauge on my 47 9A Roadster only goes to "2" - about quarter full - although tank is full. If I disconnect the sender it goes to full, if I bridge the terminals it goes to empty. Is this right? I thought it would be the other way round? I've bought a universal 30 ohm sender but connecting that remotely it only goes to less than half when the arm is fully up. Help!

[tvdwerf]

I took both the senders from my 1950 roadsters out, and found out at least one problem: rusty, and not a full movement.
I ordered a gasket from the web, it is the same as the Morris minor gasket, and took him out and look if he has an internal leak, or was hanging halfway.
I had to clean both of them and am waiting now for the wiring loom to test before mounting.

An universal sender has an universal resistance.
So you have to "calibrate" the sender by bending and or mounting an extra resistor in serial when bending is not enough.
To calculate the resistor, measure the original one, and then the universal one to see the difference.

But I should try to repair the original

[ColinB]

Hello Peter. I posted this same response to your Facebook question: your gauge responds correctly to shorting out or disconnecting the sender so I presume that you need a sender with a wider range (perhaps 0 to 90 ohms). Brian is the expert on the Forum so hopefully he will confirm this or correct me.

[mister bridger]

Thanks. I'll get the original out this weekend and see if anything can be done with it.

[jeans_old_man]

Hi Peter,
I don't know much about Roadsters but it does look like you need a sender with a 0-90 ohms range. These are more common than the earlier 0-30 ohm types. Here is some information I have gleaned from the web:

Ford up to 1986 - 73-10 Ohms
Ford 1987 & up - 16-158 Ohms
GM up to 1964 - 0-30 Ohms
GM 1965-1997 - 0-90 Ohms
GM 1998 & up - 40-250 Ohms
Mopar up to 1986 - 73-10 Ohms
AMC 1950-1977 - 73-10 Ohms
Autometer -240-33 Ohms is the most common however other ohm ranges are made
Classic Instruments - 240-33 Ohms (excluding vehicle specific gauge kits which use factory ohm range)
Dolphin - 0-90 Ohms
Dakota Digital - Programmable to work with most Ohm range senders
VDO - 10-180 Ohms

The first number represents the empty Ohm reading and the second number is the full reading.

I hope that helps.
Brian

[mister bridger]

That's great thanks. I had to wait an annoyingly long time for the 30 ohm one to come from America. Can't seem to find a supplier this side of the pond or outside China that does the universal fitting type so I'll see if I can do anything with the original one in the car first.

[ColinB]

If you can get the arm on the old one to move through its arc (or even part of it) you can put on a multimeter or link it to the gauge and check the range. At least this will tell you what you need to buy even if the old one won't work well enough to re-fit.

[jeans_old_man]

Or you could buy both a sender and a gauge together. I ordered a cheap 'universal' gauge and sender from the internet. This gauge requires a sender with 220 ohms empty and 20 ohms full. Fortunately, the correct sender came with it.

The plate on the sender is just a simple steel disc that can easily be adapted to suit the tank. The bezel on the gauge was black so I ordered a chrome one from elsewhere on the net. I printed a new dial on a plastic label and this is the result:

20181203_184256.jpg (76.19 KiB) Viewed 6952 times

[mister bridger]

Gauge looks great, but mine is in a segment of the right hand clock along with oil and amps. The sender looks very similar to the one I bought, but 0-30 variant. They seem to make them in a lot of different resistance ranges

[ColinB]

Yes you can get a 0-90 one from the States. I bought a 0-30 one for my Coupe and it arrived quite quickly. The only glitch was paying VAT before the Royal Mail would deliver it (no customs duty on low value items).

[mister bridger]

Well that was a result! Old sender unit came off with no problems, and the float arm was seized solid. A bit of WD40, and a lot of jiggling back and forth and I now have a working fuel gauge. For future reference the original is indeed 0-90 Ohms. Anyone have any use for a brand new 30 ohm universal one?!

[tvdwerf]

So the same as mine, in 80% cleaning is a nice repair

[wmcvey]

Hi Peter,
I don't know much about Roadsters but it does look like you need a sender with a 0-90 ohms range. These are more common than the earlier 0-30 ohm types. Here is some information I have gleaned from the web:

Ford up to 1986 - 73-10 Ohms
Ford 1987 & up - 16-158 Ohms
GM up to 1964 - 0-30 Ohms
GM 1965-1997 - 0-90 Ohms
GM 1998 & up - 40-250 Ohms
Mopar up to 1986 - 73-10 Ohms
AMC 1950-1977 - 73-10 Ohms
Autometer -240-33 Ohms is the most common however other ohm ranges are made
Classic Instruments - 240-33 Ohms (excluding vehicle specific gauge kits which use factory ohm range)
Dolphin - 0-90 Ohms
Dakota Digital - Programmable to work with most Ohm range senders
VDO - 10-180 Ohms

The first number represents the empty Ohm reading and the second number is the full reading.

I hope that helps.
Brian

Would you know the fuel sender I should be trying to find for my 52 4AD (Ohms wise, or part #) ? Mine has none, someone took it out I guess ?
Or would you think I should just get a set (sender + gauge) and go with that ? Thanks, Bill

[ColinB]

From previous posts on here I think you need a 0 to 90 ohm sender William. Personally I would keep the original gauge and buy the sender.

[wmcvey]

From previous posts on here I think you need a 0 to 90 ohm sender William. Personally I would keep the original gauge and buy the sender.

Thanks for the input, what is the consensus on a replacement sender. Trying to find an OEM sender (used) from somewhere in the world, or getting something new that just fits. And I have no clue where to look for that, any suggestions ?