Cannot fill gas tank to capacity

[ifinallyhaveane30]

Hey everyone,

I need some help diagnosing a peculiar issue on my '90 325i. I recently drove it over 400 miles from the town which I purchased the car in. I was using 91 octane Shell gas the whole time with Lucas Oil injector cleaner on each fill up. I am only able to put around 7-8 gal/26-30L of gas in the tank. After 7Gal of gas is put into the tank, the gas pump clicks. Once I turn on the car, the guage reads 7/8th tank. I'm wondering why I cannot seem to fill the tank with the full 63L. Is it that the guage is broken? I am tempted to just run the car out of gas and then fill it up from there to know exactly how much gas the tank can take. Thanks so much.

[Brianmoooore]

Is the instrument cluster the original?
Is the fuel tank the original?
Have you ever seen the low fuel light on?
The low fuel light is usually very reliable, but is not set to come on when the needle drops to the orange painted part of the scale, as a lot of owners assume, but only when the needle is into the section that actually lights up. Keep a can of fuel in the car, and drive it until the light comes on. At this point you will have at least 30 miles worth left.

[paultv]

Remember to do your maths correctly!

One uk gallon is 4.546 liter.



Paul

[ifinallyhaveane30]

I reached out to the PO and he said “i always just thought the tank was 7 gallons” lmao. The instrument cluster is not the original. It’s some M carbon fiber one that looks like crap. The gas light has never come on. I’ve taken the measure to get a gallon of gas in the car to do an experiment on as you’ve mentioned.