Fuel Gauge Problems

[GOZER]

Hello, I have a 1989 bmw 325i and I cant seem to get the fuel gauge to read anything, I tightened the ground nut on the back of the cluster and I also cleaned out the Fuel sender, what else can I do that can possibly solve my problem?

[82eye]

is it getting signal ? it's possible the sender has failed.

[GOZER]

I tested the sender and it does work, depending on where the floater is in the sender, it gives me 0-60 "Ohms" so I know its good, but I may have narrowed it down to the wires from the gauge to the sender, how do I test that?

[82eye]

I tested the sender and it does work, depending on where the floater is in the sender, it gives me 0-60 volts so I know its good, but I may have narrowed it down to the wires from the gauge to the sender, how do I test that?

pretty sure it goes sender to ecu to gauge. would have to test at the ecu and the gauge. if you haven't got one yet download an etm for your car and year from here : http://wedophones.com/Manuals/BMW/

that will have everything you need to trace the issue. make sure you save a copy, the resource isn't likely to be around much longer.

[It's Soda Not Pop]

pull the cluster and add some solder to the board. Mine did this

[PEZ2]

A couple of things, you have two senders in an 89 wired in series. Both have to be working for the gauge to work. The test for the sender is usually conducted with resistance check not voltage. Hopefully “ 60 volts “ is a typo. If you haven’t downloaded the 89 ETM yet the pic below is an 89 image of the sending units.

[GOZER]

So if my car starts and drives, my left fuel sender may be bad in some way to not make the guage work? and where did you have to soulder to repair the board, and which board the SI board or the board that holds and the bulbs and clusters?

[GOZER]

I would have to check continuitey between the two pumps maybe? Or would the left sender also have a sensor in it like the one on the passanger side?

[AWDBOB]

it is common for the main board in the cluster to have cold solders, but in my experience, that typically causes a jumpy gauge, rather than an inop gauge. I haven't had a bad main board that causes no fuel reading at all, but I'm sure it's possible. also worth noting there should be a washer in between the fuel gauge and the main board, as well as a washer under the nut on the back.

Jump the chassis harness plug for each fuel sender while watching the fuel gauge, which is pretty easy to do with a jumper wire to help hone in your diagnosis

[GOZER]

I have figured out what the problem is, I tested the continuity between the right and left fuel sensor wires and I figured out the wires have rubbed through and are broken. Without dropping the tank, how do I get those wires loose so I can repair them? The wires that are broken are on the drivers side and the wires are heading towards the rear of the fuel tank.

[82eye]

it's mapped out above in the pic from the etm.

edit : mine were loose. just used a hook to draw them in. did not have to drop the tank. perhaps mine are not secured correctly.

[AWDBOB]

I have figured out what the problem is, I tested the continuity between the right and left fuel sensor wires and I figured out the wires have rubbed through and are broken. Without dropping the tank, how do I get those wires loose so I can repair them? The wires that are broken are on the drivers side and the wires are heading towards the rear of the fuel tank.

Remove the rear tank bolts by the subframe only, and it'll drop down enough for you to snake the wiring out to repair it

[GOZER]

okay ill try that, thank you everyone for helping me so far!

[GOZER]

Also, are the bolts you are talking about the two bolts at the rear, right under the subframe?

[AWDBOB]

Also, are the bolts you are talking about the two bolts at the rear, right under the subframe?

No, I’m referring to the rear fuel tank bolts that would allow it to drop down

you access the bolts via the space in between the subframe and the fuel tank