Fuel gauge issue

[BosstinPop]

Hi all, first post here as I’m a pretty new owner of a 940 estate.

Got a weird issue with the fuel gauge that is annoying me and especially the wife when she borrows the car!

Having filled the tank, the warning light is on and the gauge reads empty, but by the time I’be used most of it up, the light is off and the gauge reads around 1/8th full.

I know the previous owner had swapped out the cluster due to a Speedo issue, I can’t see any issue at the sender end, but having read up a few things I’m wondering if he’s put in a cluster from an earlier model, where the fuel gauge is is set up different? My estate is a 94, am I right in thinking the earlier clusters are different?

Thanks in advance, Tom

[360beast]

The very early gauges wire up differently so he wouldn't have been able to fit earlier gauges, the most likely culprit is dry solder joints on the fuel gauge itself.

[Forrest]

In my experience if the light is on then the gauge is getting what it thinks is an empty (higher) resistance reading from the in-tank float. If the gauge is reading empty but the warning light isn't illuminated then the more likely culprit is the PCB behind the dash.

I'd suggest some testing using the information from the FAQ as a guide.

https://www.volvoclub.org.uk/faq/Ele...augeFluctuates

I must admit that I usually just short sensor connections to see if gauges are working but more correctly you should use resistors of the appropriate ohms.

One possibility would be the two long contacts in the sender coming loose. I have seen this happen in a secondhand unit that came to me via the mail. This could result in a situation where with the float near the top (tank full) the sender is open circuit (high resistance = empty) and as the level drops it finds a point where it jams across the contacts and gives a misleading, static reading.