Fuel Reading Issue

[E30325]

I have an issue wih the fuel gauge not reading correctly. The gauge does not show full when the tank has been filled. I replaced the fuel gauge and fuel level sensor but the reading is wrong. It initially read correctly after replacing these parts, but it's not reading correctly - only 3/4 full when it should read Full.

• Do I need to also change out the fuel sending unit?
• What are the readings for checking the current?
• Any suggestions?

[reelizmpro]

What year and model is your car? Seems strange that it fixed the problem initially and then started reading 3/4. That sounds like a resistance issue in the wiring between the level sender and the gauge but before you get into that there are other things to consider. Did you install the correct gauge for the fuel tank size? Is the tank dented? Any pics of the car and the tank?

[E30325]

The E30 is a 1989 325i. I ordered and installed the gauge referenced in the OEM parts manual (# 62131381886). The tank is not dented. I unplugges the connection on the driver's side and the fuel gauge stopped reading, so I assume an issue could be here. If there is a resitance issue, what should be the reading so I can measure?

Here are pictures of the tank access under the rear seat.

[reelizmpro]

You have two fuel level senders, one on the driver's side and one on the passenger side. The gauge sees the resistance of both of them in series.

Here's a good thread with some numbers.

https://www.bimmerfest.com/threads/e30-fuel-system-question.706905/

https://www.youtube.com/watch?app=desktop&v=5OXdkznEILw

Check to make sure both level sensors are good before to rule them out.