Dancing fuel gauge!

Post Fri Dec 30, 2016 12:12 pm

Hi fuel gauge on my 325i has just started playing up.
It's dancing all over the place! Any ideas what it could be?

Post Fri Dec 30, 2016 12:24 pm

Brass nut on the back that earths the gauge to the circuit board?

Post Fri Dec 30, 2016 1:42 pm

DHFiS wrote:Brass nut on the back that earths the gauge to the circuit board?

That's the first thing to check. Try tapping the top of the dashboard sharply, and see if it has any effect on the gauge to confirm.
Nut is on the back of the cluster case, right behind the gauge. Temperature gauge has one as well, so check that at the same time.
If this cures the problem, then case closed, but if it doesn't, then the problem is likely to be with one of the two level senders in the fuel tank.
Either post again for instructions on how to determine which sender is at fault, or use the search function to look back at previous posts where I've described how to do this.

Post Tue Jan 03, 2017 6:02 pm

OK had the dash out a few times recently so that might be it.
Thanks.

Post Sat Jan 21, 2017 12:34 pm

Checked the nut behind dash it's not that. Must be the senders?

Post Sat Jan 21, 2017 1:44 pm

M3KUK wrote:Must be the senders?

Probably A sender. Unlikely to be both.
Ensure that you have less than half a tank of fuel, then remove one of the inspection panels under the rear seat base, pull off the sender plug and use a short piece of wire to short out the pins in the plug, then drive the car as normal.
The gauge will read twice what it should, but you are looking to see if the gauge still jumps.
Replace the plug on that side, then remove the cover on the other side and repeat with the sender plug there.
When you determine which shorted plug gives a stable reading, the faulty sender is the one still connected on the other side.
Some versions of the sender can be dismantled and repaired.

Post Sat Jan 21, 2017 4:13 pm

Thanks Brian will give it a go.

Post Tue Jan 24, 2017 8:24 pm

Looks like it's the sender on the passenger side. It stops jumping around with it shorted out.
The fuel warning light still works ok funny enough!

Post Tue Jan 24, 2017 8:28 pm

M3KUK wrote:Looks like it's the sender on the passenger side. It stops jumping around with it shorted out.
The fuel warning light still works ok funny enough!

That will be the problem then!
Only time I've known a low fuel level switch to fail is when the whole RH sender has been severely physically damaged by some uniformed muppet trying to remove the fuel pump without removing the sender first.

Post Wed Jan 25, 2017 8:38 pm

Yes looks like it, thanks. I'll remove it when I get a minute.
Low Fuel light is on the other side sender, so at least I know
when there's 1.5 Gal left.