Fuel guage shenanigans

[Stu]

Here's the deal:

I swapped out my instrument cluster for one out of a '90 325is. All is well, however, the fuel gauge needle only uses Full to the 1/2 way as the sweep. In other words, when I have a full tank..it reads full, but when empty, it's at the 1/2 tank mark. The fuel light comes on when I have 1-2 gallons left, as normal.

My sister had the same problem on her '85 318 years ago, never to be figured out.

Any ideas?

[PanamaE30]

Jesus tell me when you figure it out..

My fuel gauge is the craziest thing on earth.. I turn to the right, it goes up. I turn to the left, it goes down.

I'm continually putting gas in the car because after a certain point i can't know exactly how much gas i have in the vehicle. it really sucks :(

[aaron_silva]

I was going to guess the sending unit but both the 318 and the 325 use the same one. You could still check the sending unit. My gauge has been messed up for a year so I finally took out the sending unit. I noticed that the small (very small) wires inside the unit were not attached. I was able to reattach one of them, but the other one was too short. I re installed the unit and now I have a full tank all the time. I have a new unit on the way.

BTW- You only need a screwdrive and a small socket (4mm?) to open the sending unit. Do it when you are low on fuel.

Panama- Keep track of you trip meter when you fill up. That is how I know when I am low on fuel.

Aaron

[Stu]

Panama, yours sounds like the ground nut behind the fuel gauge is loose. I had the same problem, the fuel gauge seemed to work like a G-meter. ;)

Aaron, I will check that out. There is a possibility I didn't reconnect the wire(s); I rushed to install the thing.

[PanamaE30]

Panama- Keep track of you trip meter when you fill up. That is how I know when I am low on fuel.

Aaron

Trip meter? What trip meter? Like just about everything else in my car,it's broke :P
I really need to sit down and make a to-do list.. :(

[PanamaE30]

Panama, yours sounds like the ground nut behind the fuel gauge is loose. I had the same problem, the fuel gauge seemed to work like a G-meter. ;)

I'll definitely check into that, thank you.

[hella 325]

My gauge has also been swapped, but mine reads 1/4 tank below empty to 3/4 tank full (aka at full mine is at 3/4 but at emtpy its WAY WAY below emtpy. Also i have a huge dent in my gas tank from some A$$ hole that tried to use a floor jack on the tank to raise the car. (anyone know how to fix that)

[Stu]

My gauge has also been swapped, but mine reads 1/4 tank below empty to 3/4 tank full (aka at full mine is at 3/4 but at emtpy its WAY WAY below emtpy. Also i have a huge dent in my gas tank from some A$$ hole that tried to use a floor jack on the tank to raise the car. (anyone know how to fix that)

The crunched fuel tank is common. When putting the car on a 4-pt lift, a lot of stupid mechanics don't do it properly, slide the metal jacks under the car and raise it up, not knowing they're crushing the fuel tank. That could be related to your fuel gauge problem, but with my knowledge on fuel gauges, it's a shot in the dark.

[niq_nak]

Jesus tell me when you figure it out..

My fuel gauge is the craziest thing on earth.. I turn to the right, it goes up. I turn to the left, it goes down.

I'm continually putting gas in the car because after a certain point i can't know exactly how much gas i have in the vehicle. it really sucks :(

i have the same problem. today my gauge was a little over a 1/4 tank, but the cpu said i had 22 miles left while getting 19.9 mpg. next time i turned on the car it was on top of empty.

[chrisd]

Mine reads full for the first 100 miles, then goes down smoothly. It's as if I were overfilling the tank by 4 gallons above capacity... Maybe the sender is sitting lower in the tank than it should...

[PlatinumX]

Fuel guage calibration

Arrgh!! I'm having the same problem: after a fill up the gauge reads full for about 80 miles, then goes empty a little under the 1/4 mark. The low fuel light works properly, about 30 miles before I run out of gas.

Has anyone figured it out? I've already replaced the sender.

[Bryson]

stu, the gauges differ on the cars with different tanks. swap your old fuel gauge from your 318 or an early 318 (any e30 with the small gas tank) and it will work fine
I went through this when using an m20 cluster in my 318 w/ the little tank, then I converted to the big tank after putting in the right fuel gauge for the little tank, so I had to swap it again
BMW lists the same part number for both gauges, but they are not to be believed! haha, just swap em man

[dwforum]

My fuel gauge is off as well. It runs to empty fairly quick, but I always have another 5 galllons in there when it is past empty. If Anyone knows a way to fix a faulty fuel gauge, I'd love to hear as well.

[Stu]

stu, the gauges differ on the cars with different tanks. swap your old fuel gauge from your 318 or an early 318 (any e30 with the small gas tank) and it will work fine
I went through this when using an m20 cluster in my 318 w/ the little tank, then I converted to the big tank after putting in the right fuel gauge for the little tank, so I had to swap it again
BMW lists the same part number for both gauges, but they are not to be believed! haha, just swap em man

Thank you!
You the man Bryce :!: