Need an expert / wizard to help solve empty fuel gauge issue !!!!!!!

[Dinan4.6is]

Let's start from the beginning. It's a long story, and I am not exactly sure what's relative or not...
2003 X5 4.6is

- I decided to remove my instrument cluster in an attempt to DIY pixel repair my LCD display. I ended up ruining almost all of the gauge stepper motors due to the crappy tool included in the DIY kit that's supposed to hold the stepper motor pins while removing the gauge needles. This "tool" doesn't work at all, please don't try it.

- I then sent my original cluster to "Fixels" to have it completely refurbished. In the meantime, I purchased a spare used 4.6is instrument cluster. Everything worked fine, including the fuel gauge. Eventually, my fuel level got down to empty, and the warning light came on with the OBC display showing "Range ---". I usually don't let the fuel level get this low, but it wasn't the first time its happened either.

- I stopped and put about $30 in, I always use 93oct Premium gasoline. This was the first time this issue happened, as I got back in the car and the fuel gauge remained empty along with the warning light on and OBC display still showing "Range ---". I found this very strange and immediately stopped at another gas station just up the road to fill up the rest of the car’s fuel tank, assuming it was a random glitch that would be corrected with a full tank. Unfortunately, the empty fuel gauge and yellow warning light remained.

- My only conclusion was that this issue must be some freak glitch due to the instrument cluster not being the original one installed at factory in this particular car (this was the used spare I had purchased while my original was being refurbished). So then I decided to wait to until I got my original cluster back in. Unfortunately, after receiving my original cluster and refitting it, the same problem remained — empty fuel gauge and yellow warning light.

- Not having any diagnostic equipment, I took the car to my indy tech and found a code for "fuel sensor 1". He told me that fuel sensor 1 was the right fuel level sending unit which was attached to the fuel pump assembly. I purchased a genuine BMW fuel pump assembly, and properly installed it.

- I even tried ANOTHER 4.6is instrument cluster from my tech's car with the same result — every other part of each cluster functioned perfectly, but all 3 clusters showed the same fuel gauge issue. So I put my original refurbished instrument cluster back in.

- A week or 2 later I was changing the car's engine oil and had both front wheels up on ramps with the car on an incline. After the oil change, I turned the car on to let the oil temp warm up. After 5-10 minutes I got in and suddenly realized the fuel gauge worked again. I thought maybe being on an incline freed up something that had been stuck. It showed about 1/2 tank with "Range 160 Miles”. I thought the issue had finally sorted itself out, but after driving and getting down to 1/4 tank or so and I stopped to get more gas. Unfortunately, the new fuel I added did not register and the gauge level remained the same. As I continued to drive the fuel gauge and OBC range levels continued to decrease until they finally went back down to empty with the yellow warning light on, and OBC back to "Range ---".

- After exhaustive research on the subject, I come to find out that "fuel sensor 1" is actually the left fuel level sending unit, NOT the right side attached to the fuel pump assembly as I was originally told. I purchased and fitted a new unit with no results.

- Only now, the engine was not getting any fuel and the car wouldn't start

- I knew it couldn't be a faulty left fuel sending unit, as it was a new part fitted correctly. Also OBC "Test 06" was reading the correct fuel level from the left side, but the right side was reading zero (0.0). For example, if there were 40 liters of fuel in the left side of the tank "Test 06" read (40.0/0.0/40.0). But it also couldn't be a faulty right fuel pump assembly, as this was also a new part fitted correctly.

- Turns out I somehow messed up the fuel tank syphon jet unit while replacing the left fuel level sending unit to install the one so the fuel from the left side of the tank was not being syphoned over to the right side of the tank where the pump is located. I assumed this also explained "Test 06" reading zero on the right side of the fuel tank. So, I purchased an entirely new fuel tank syphon jet pump with all of the hoses and properly installed it. Luckily, the fuel was once again being syphoned from the left side to the right side where the pump is, and the car started right up. Unfortunately, the fuel gauge still read empty. However now, OBC “Test 06” also continued to read zero (0.0) for the right side, even though there was surely now fuel in it.

- Losing all hope I thought maybe the fuel filter is somehow blocking the fuel gauge and ONC “Test 06” from getting a signal. So, I properly installed a new genuine fuel filter with no result.

- I tried resetting the instrument cluster in every way possible. OBC "Test 21" / removed & checked fuses 1, 43, 45 / reset service interval / etc. No result.



Side notes:
- "Test 02" (the one that makes the cluster test all of its lights, functions, and gauges) does perform as it should. Along with the other gauges, the fuel gauge also does go through its normal course from empty to full and then back down to empty.
- I also properly rebuilt my fuel injectors.

Summary:
- Fuel gauge reads completely empty with yellow warning light and OBC shows "Range ---".
- "Test 06" reads proper fuel levels for the left side, but constant 0.0 for the right side. The total reads whatever the level for the left side is. For example: (40.0 / 0.0 / 40.0)
- Fuel injectors, fuel filter, right fuel pump assembly, left fuel level sending unit, and fuel tank syphon jet tubes are all new Genuine BMW parts that have been properly installed.
- I've tried a total of 3 different correct 4.6is clusters, all with the same exact results — function 100% aside from the empty fuel gauge.
- I have reset the cluster in every way possible.
- "Test 02" does prove the fuel gauge itself does function and the needle is not stuck.

** I realize this is a lot to read and comprehend. I thank anyone who does so in advance. Any help is greatly appreciated. **[/CENTER]