Fuel level reading not correct, what's up?

[91 318is]

Posted this in the electronics section, might get more luck here so I copied and pasted.

Long story short, cluster was swapped out and now the fuel gauge is reading 1/2 tank when fuel tank is almost empty, and the low level light comes on. I read around and seemed like a normal problem with swapping early model clusters into late model cars. I got a working gauge and matched the part #'s with realoem's correct part # for my car, swapped it, and is still not correct. I also swapped the fuel level sender, that obviously didn't help.

Oh and I also, I checked to make sure the little box that plugs in the front of the cluster is the correct one and it's the blue one, which is for the 318.

Anyone have any idea?

[Jean]

So you have a late model car yes? It has TWO senders, they work together as they are connected in series. Have you checked them both? If one is OFF, reading will be OFF.

The fuel gauge in your cluster needs to be from a late model car as well. Basically it needs to be from a car that had TWO senders.

[e30Matt]

Yep, dead on the money. You can swap a fuel gauge by itself into an early cluster and be OK, though. The difference is entirely in the gauge.

[Kershaw]

i had this issue. i swapped a late model cluster into my early model car, because the car came with an eta cluster and i put an i engine in it.

all i did to fix it was swap the old fuel gauge into the new cluster.

[91 318is]

Yes I have a 91 318is.

So there is 2 senders in my tank? I only saw one when I took the cover off under the rear seat (I think I did).

Well to be honest, I'm not sure if it's a early model cluster or not. All I know is after the cluster was swapped, the fuel indication hasn't been right since. I installed a new, correct part number fuel gauge yesterday and that didn't fix it, made sure the code plug on the front of the cluster is correct, and it is.

Thanks

[91 318is]

Just looked on realoem and they're listing ONE fuel sender in the tank?

[Jean]

One is on the passenger side in the fuel pump assembly, and one is on the driver's side. Look again.

[91 318is]

One is on the passenger side in the fuel pump assembly, and one is on the driver's side. Look again.

is the sender seperate from the pump assembly?

9 is the only listing they have for a sender?

[Jean]

#9 is the thin sender inside the pump, there is also another sender on the other side of the tank..it's about 2x as thick. It's not pictured. Just pull the seat and look for a round cover.

[91 318is]

#9 is the thin sender inside the pump, there is also another sender on the other side of the tank..it's about 2x as thick. It's not pictured. Just pull the seat and look for a round cover.

fair enough. I'll be back.

[91 318is]

Pulled the seat and the cover. Pulled it off and nothing's under there. So apparently I only have one sender.

What's next?

[e30Matt]

Apparently 318is's only had one sender, just checked RealOEM for myself, and it only shows one. Strange. You may have a bad sender then, you can remove the four 8mm nuts on top of the fuel pump assembly and pull the sender from the tank, just make sure to have a bucket ready as it will pee fuel all over the place when you pull it out.

[jlevie]

318's only have the single sensor mounted with the pump. Unless there is something wrong with the new sensor the gage only going to half way when the tank is empty is caused by the wrong fuel gage being in the cluster. Pull the gage from the old cluster and install it in this cluster. Or go to a dealer and buy a new gage whose part number is correct for this car.

[91 318is]

It's a brand new VDO sender in it, and it's reading the exact same as the old sender.

Also, swapped the gauge out with another gauge that is the correct part # for the car. It's been confirmed with realoem.


So new sender, and correct fuel gauge and it's still not working.

[Jean]

Oh sorry, I didn't know late model 318i cars only had one sender and not 2 like late model 325i cars!