OBC not logging mpg on e34

[htspecialist]

I have a 1989 535i with 223,ooo miles on it. I changed the light bulbs a while back otherwise everything has been fine with the OBC until a few days ago. I began getting quickly declining mpg readings on mpg1 and mpg 2. Also the "range" became a little erratic and the fuel level on the instrument panel began to give varying readings. I reset the mpg1 and mpg2 using the s/r button on the OBC and now get "---.-" on the mpg1 and mpg 2 read out.

I made sure all the fuses are ok and with the guidance of this board unlocked the OBC. I suspect the fuel tank sensor gauge could be the culprit. I found a site that describes removal and cleaning of the fuel tank sensor gauge on an e32. The level of effort to fix this seems a little comprehensive. I have some questions.

Has anyone expreienced a similar problem in an older e34 and how did they fix it?

Is it safe to assume that the e32 and e34 have vary similar fuel tank sensor and sending set ups so I can follow the e32 tutorial?

Should I just go out and replace the sender and is there an affordable source for this part?

Thanks

[Ross]

I cant think of another component to effect the OBC and fuel gauge like that. Before you change it though check the connections and ground first, I'll bet thats it.