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so im worndering if anyone feels like helping me out, Im sure you have all seen or heard about my swap. I need to figure out what kind of signal the fuel level sending unit sends out so i can get an autometer fuel gauge. I know that 99% of most cars out there use an ohm reading for full and empty but i have no idea what the 8 does. so if anyone here could help me out that would be awsome.
There are 2 sending units...one in each side of the tank...not sure what the PCM does with the readings...it might add the values together to come up with a value? or it might be logic in the PCM...never really looked at the wiring dia to see if they are seperate imputs into the PCM
If they are wired in series then it will likely be a varying resistance value that you might be able to scale to work with an aftermarket guage
It's not handled by the PCM, its handled purely by the instruments.
It's connected directly to the second (larger) connector on the back of the clocks, pins 2T (B/O wire ) and 2R (R/L wire) are for the "Fuel gauge sender unit (main), pin 2P (W/G wire) is for the Fuel Gauge Sender Unit (Sub).
As far as I can tell from the diagram there should be two (variable) resistances, one between B/O and W/G for the "Fuel Gauge Sender Unit (SUB)" and one between B/O and R/L for the "Fuel Gauge Sender Unit (Main)"
If it bothers you that much just mod the gauge cluster. Pull that gauge out and custom mount the autometer in its place. It wont be perfect looking but it will function just fine.
Still no answer on what Ohm Readings the 8 has and what gauge one would need to order if they wanted to use a different Fuel Gauge with the stock fuel tank for example...
We need to further this thread and get more info on this. Because I currently have a fuel cell in my 8 and would like to utilize the OEM fuel gauge. What DocBeech said isn't as easy as it sounds. I've pulled the whole cluster apart and it would be no simple task to fab an auto meter gauge in its place
Disclaimer: I’d make a new thread if I could but I have not commented on 10 posts w my new membership, sorry but I do t want to make BS comments just to get there
I need to know if anyone has successfully installed an after market fuel gauge. I have a 2004 w LS swap that was done by PO, but I am cleaning things up to make it more factory like vs. street racing.
no, starting new threads is one of the top 3 mistakes forum noobs make.
did you try contacting member “stubbs” for his advice? He understands the LS swap issues as good or better than anyone. Nobody in this forum area is doing aftermarket gauges like your setup. You need to go to the non-rotary engine swap area:
but just so you understand, the RX8 feeds those two signals to a small ecu in the dash display and it correlates it to a dash gauge signal. I might have what you need though. Let me check.
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I have one of these NITB and am not going to need it. When connected to the correct signal wire to the fuel gauge it will convert the resistance reading to volts as per the setup below. It was originally designed for Spec Miata racing with also has the same basic fuel tank setup as the RX8. Just pm me.
Iron Canyon Motorsports (ICM) Fuel Level Sensor – VERY COOL !!!
I had to find correct wire in OEM instrument cluster for fuel level:
Here is fuel level sensor spliced into cluster harness and tied down:
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4th May 2013, 16:35 #5bocon
Fourth gear I jumpered the fuse for the fuel pump and used my cool fuel test port to empty the tank completely (after, I tried to start car and it would not). I then connected lap top to EVO4 logger and went into AiM Race Studio software for custom sensor calibration. With car on level ground and key in the ON position (engine not running), I measured one gallon of fuel and put in tank. I then waited a few seconds and recorded the millivolt reading from ICM sensor on laptop. I did this 11 (ELEVEN !!!!) times until I had eleven gallons in tank (this takes a while). So I had 12 sensor reading for 0 to 11 gallons.. You then tell Race Studio you want to convert these readings into gallons and you are done. Sensor worked flawlessly at Barber in April. However, when MXL Dash warning light went on for < 1 gallon I exited track immediately since I still want to double check readings with engine running. Out of 5 sessions, light only went on once (during Chin 90 min “happy hour” session at end of day). I usually start a 30 minute session with 5 gallons (sometimes 4.5). Depends on how many yellows I expect
I ordered it for the correct ohms range for an S1 RX8:
11-06-2008, 01:20 PM
4th May 2013, 16:35 #5 bocon 
