90 325i fuel gauge not working

[bfdbatt2]

started it sat morning, fuel went to full, down to half, up to full, down to empty, back and forth. fueled up.....took about 1/2 tank. been pegged at full for 2 days and probably 125 miles, hasnt moved. swapped fuel gauge out today.....for a working one off an 87 325i and seemed to be working when i got it put back together, reading at 3/4 tank. drove to work 45 miles and needle is pegged at full again....

thoughts? float?

thanks.

[atomic]

I am currently having the same problem with my '91 325i and have changed out the both tank sending units. And still have the always full reading so I have just gotten my hands on some fuel gauges that I will be swapping out this week to see if it fixes my problem.

I will tell you there is 2 different fuel gauges for the e30's. One is for the 12 gallon tank (pre '87 ? )and one is for the 16 gallon tank (post '87 ? ). I am not postive on the cut off years for the different tanks and what models they were used in. So you need to make sure the gauge you use is a 16 gallon tank since yours is for sure the 16 gallon

[rs4pro3]

cut off was 8/86 I believe, which is when BMW changed a lot both electrical and with going to the 16 gallon tank with a single pump

[bfdbatt2]

replaced from an 87

yeah the replacement gauge was from a 325i built 2/87, should've been fine, guess i will move on to the sender...