RE: <E30> Quirky fuel gauge

["William R. Dieter" <dieter@xxxxxxxxxxx>]

> Date: Fri, 27 Apr 2001 12:13:23 -0500
> From: "Fadeev, Alex" <alex.fadeev@domain.elided>
> Subject: RE: <E30> Quirky fuel gauge
> 
> Daniel L Adams [mailto:dadams@domain.elided] wrote:
> > 
> > I have an interesting problem with the fuel gauge on my 1987
> > 325IC. It gets stuck on "full" when I start the car. Sometimes 
> > tapping on the front of the dial (in true Hollywood style :-)
> > brings it to the correct level, and sometimes it drops to the
> > correct level on its own after driving for a while. Like all 
> > good problems, it's intermittent.
> 
> Daniel,
> I am totally guessing here as I never had this problem on my E30. When I had
> the instrument cluster out I noticed that both the temperature and fuel
> level gauges are bolted to the cluster board. The temp gauge uses that
> connection for the ground and goes haywire when that connection gets
> intermittent. 
> Could the fuel gauge be also using the mounting bolt for the ground? If it
> does, try tightening the hex nut that holds the gauge to the instrument
> cluster and see if that helps.

That's exactly right.  I had the same problem with my fuel guage.  I 
removed the instrument cluster and rubbed the nut, bolt, and contact on
the board with steel wool to remove the oxidation.  I also added a bit
of solder on the board an reflowed what was there.  I don't know if
reflowing the solder was necessary but the instrument cluster was such
a pain to get out I didn't want to have to take it out again.

There is an article at

<http://www.bmwe30.net/cgi-bin/technical/index.cgi?db=default&uid=default&ww=on&ID=22&view_records=1>

that describes the problem in more detail.

> > Here's the quirk though...  If I press, and hold down the 
> > trip milometer reset button (the mechanical one, not the OC),
> > the fuel gauge shows the correct level! When I release it, 
> > the needle springs back to "full" again.  Weird eh?

I don't remember that, but I don't think I ever tried it...

Bill.

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