Problem with fuel gauge

[Kwaaahhh]

I'm in need of you guys guidance on this. Ok first off before anyone says search I did already and I still can not figure this one out. I tried troubleshooting all the problems that lead to the faulty fuel gauge. First I checked the fuel leveler unit and replace it with a new one. No movement on the needle after this was done. Second I read that it could possibly be a bad SI board. So i went to the yard and got this:
2 VDO Si board (90 325i)



(91 318)


2 VDO fuel gauge (Same as above)

First off mine cluster is a MOTOMETER, but i read that VDO should be ok. Right?

Well I tried swaping only the 325 vdo si board since it looked more compatible to the moto meter board today. Also tried swapping the 2 different fuel gauge. Turned on the car and still nothing. I'm stuck right now and can't figure wtf is going on. What should I do guys? Should I start looking for motometer components? TIA!

[jlevie]

Check the resistance at the connector to the cluster. You should see it go from zero (full tank) to 74ohms. I'm not positive on the empty tank resistance, but if you don't see a large change in resistance when you invert the level sender, there's a problem with the wiring.

[lordofthewaters]

Now you know that on later models there are 2 fuel level senders right? One with the fuel pump, and one on the other side as well. I'd check both to make sure.

here

[Kwaaahhh]

Check the resistance at the connector to the cluster. You should see it go from zero (full tank) to 74ohms. I'm not positive on the empty tank resistance, but if you don't see a large change in resistance when you invert the level sender, there's a problem with the wiring.

How do i go about doing this? So check the wiring or the cluster itself? Thanks!

[Kwaaahhh]

Now you know that on later models there are 2 fuel level senders right? One with the fuel pump, and one on the other side as well. I'd check both to make sure.

here

I pop both cover under the rear seats. The passenger side is where I found the fuel leveler unit, which i replace. The other side theres no bolts to take that part out. It looks like its stuck or welded to the gas tank.

[lordofthewaters]

You should be able to cross two flat head screwdrivers and catch the blades in the notches on the sides of the sender and turn counterclockwise and it'll screw out. I hope that made sense.

[Kwaaahhh]

You should be able to cross two flat head screwdrivers and catch the blades in the notches on the sides of the sender and turn counterclockwise and it'll screw out. I hope that made sense.

Oh ok, I'll give that a try in a bit. Thanks!

[Kwaaahhh]

ok so just check the second fuel leveler and the unit seems to fine. Not sure what to do next?

[Kwaaahhh]

Anyone?

[Kwaaahhh]

Ttt!

[Jonathan Chan]

ok so just check the second fuel leveler and the unit seems to fine. Not sure what to do next?

The level sender on the passenger side of the car controls your orange "reserve" light that comes on.

The level sender on the driver's side controls needle movement of the gauge.

When you checked the second fuel level sensor, did it have a float sliding on the thin wire?

My gauge was acting up a few weeks ago, I pulled out the second level sensor (driver's side) and the wire had broken causing my gauge to not work.

- Jon

[Kwaaahhh]

What do you mean float sliding on the thin wire?

The level sender on the passenger side of the car controls your orange "reserve" light that comes on.

The level sender on the driver's side controls needle movement of the gauge.

When you checked the second fuel level sensor, did it have a float sliding on the thin wire?

My gauge was acting up a few weeks ago, I pulled out the second level sensor (driver's side) and the wire had broken causing my gauge to not work.

- Jon

[Jonathan Chan]

What do you mean float sliding on the thin wire?

When you remove the sender from the driver's side of the car, and you turn the unit upside down, you'll see a small nut holding the guts of the sensor inside the metal cylinder.

Remove that nut and you'll see what I mean.

- Jonathan

[Kwaaahhh]

OK, so i took some advice on baye30 to jump the 2 out 3 prong on the fuel leveler plug to see if theres any movement on the needle. I was able to get the empty light to come on but still no movement on the needle.

So today I borrowed a friends perfectly working cluster and swapped it into my car. Here are the results.

His cluster in my car, key turn on every light is working as well as the needles on all the gauges except the fuel gauge. I jumped the 2 out 3 prong from the fuel leveler plug and only got the empty light on. As for the fuel needle it didn't jump to full.

I took my cluster and swapped it into his car and same thing. Everything works except the fuel gauge.

Both of our cluster when i jump the plug on the fuel levelel empty light comes on, no movement on the needle.

And of course his cluster when plugged into his car, everything works.

So is the wiring for the fuel gauge jacked up in my car?

[jlevie]

Are you sure that you jumpered the correct pins on the level sensor connector? One of the pins is for the low fuel warning switch in the level sensor. If that was one of the pins you used the only result at the gauge will be the low fuel light.