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 New 96 Fuel Tanks / Fuel Sender Replacement
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beardydave
V4 Fan

125 Posts

Posted - 26 Jan 2019 :  17:51:50 Show Profile Reply with Quote
I'm putting together the drawings for a replacement fuel tank in stainless steel, in case Fliptops group buy doesn't work out, but i'm struggling with fuel level sender options. My own was removed from the tank as a big blob of rust, with no continuity and no movement on the arm, so i'm needing a new one.

Scandix do one that is supposed to be a replacement for 1976 onwards. Mine is a 1975. Anyone know what changed that would make it incompatible?

Also the Scandix one doesn't use the brown wire on the sender. They say in the instructions that it is only an earth, but on the wiring diagrams it goes to the instrument, and there is a separate earth marked, which i'm assuming is the little black tank earthing wire that goes straight to the body.
Is the brown wire actually for the low-level warning lamp? And would this mean that the low-level light doesn't work with the Scandix sender, or is the low-level light worked out internally to the gauge based on resistance of the sender?

Does anyone know what the resistances should be for a functioning sender for full and empty in case I need to find an aftermarket sender and use a resistances converter to get the gauge to read right.

Aftermarket senders are a whole extra can o worms, as most need a deeper tank than the one we have.

green96v4
V4 Mad

Canada
737 Posts

Posted - 26 Jan 2019 :  19:50:37 Show Profile Reply with Quote
Hi Dave

you're correct about the aftermarket can of worms, I bought a VDO 226-163 thinking the resistance range was stamped on the original (follow this thread, so good info, including my incorrect purchase!!) (Resistance on 163 is 33-240 and the original has 38-228 stamped on it, but has no bearing on the working resistance)

http://www.saab-v4.co.uk/speedball/topic.asp?TOPIC_ID=26886&SearchTerms=fuel,sender

After reading this I determined VDO 226-162 is closer resistance range to the OEM, but as siad in the post, I find the gauge stays full forever and then drops to empty when the light comes on. Resistance range on 162 is 3-180

I recently found a decent condition original on Tradera, so bought that. If the Tradera purchase works as it should, you're more than welcome to the VDO's I have for "research purposes"
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gorselands
Starting Member

United Kingdom
22 Posts

Posted - 02 Mar 2019 :  13:52:27 Show Profile Reply with Quote
Sent my single unit petrol gauge to VDO for them to measure resistance -it needs a 3 - 180 ohms sender (empty/full) Having difficulty finding one in UK and then the 5 hole plate has a shroud round the connectors that would protrude into the boot floor. Contacted Smiths Instruments and sent them the gauge. They measured resistance at 5 -190 ohms and said that a standard 10-180 ohms sender unit would be within tolerance.

The 38/228 marked on the plate must be a VDO reference number. Smiths can sort out a new one albeit without the low warning light.


I ended up getting a VDO sender with low warning light but it is not the same as the original and the arm needed careful adjustment to clear the tank baffles. Shows full when full and light comes on earlier than it normally would, but it works.
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greg124
V4 Fan

United Kingdom
173 Posts

Posted - 02 Mar 2019 :  15:56:11 Show Profile Reply with Quote
I've just removed the sender from my old tank, ready for a tank swap. Ignoring decimal places I'm getting 3 to 180 ohms between one terminal and the base plate, and 40 ohms to open circuit between the other terminal and base plate. Does the latter sound about right for the low fuel warning light?

When I got the car the fuel gauge appeared not to be working so assumed it would be a faulty sender, but now I think the fuel level was just so low that it wasn't registering.
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beardydave
V4 Fan

125 Posts

Posted - 05 Mar 2019 :  05:53:13 Show Profile Reply with Quote
The 3 to 180ohms sounds right from what ive read elsewhere.

Does the 40ohm terminal vary gradually as the float is moved or is it on/off?
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