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Chasing down this fuel level sensor issue again in the 2000 camaro.
I have a racetronix hotwire kit and 255 pump and I have replaced the fuel level sending unit twice. I have a kill switch with the battery in the back and when the car is sitting, all power is cut off. So I flip the kill switch on, drive the car around, and after about 5 minutes, the "check gauges" light comes on and my fuel level gauge goes right to zero and stays there. If I turn the car off and on to accessory position, the gauge stays at zero. If I start the car, gauge shows zero. It's not until I completely cut the power off and turn it all back on, that the fuel level sensor goes back to the correct position.
I've done the trap door mod, and with the fuel gauge in the correct position and not at empty, I've wiggled the wires where the GT 280 4 way plug connects to the top of the fuel bucket and also all the wires going in and out of the MP150 factory harness. The gauge doesn't move.
I've tested the purple wires and one purple wire has 5v going into the fuel level sending unit. With power hooked up, the other purple wiring coming back from the sending unit also shows 5v so the circuit is complete.
Checking the ohms with power in accessory position everything hooked up and fuel gauge showing about 60% full, I'm getting 112 ohms on one of the purple wires, and 0 ohms on the other. I'm assuming that is normal? Grounds appear to be good. I read that the fuel level sensor range is 33 ohms to 240 ohms on 99-02 fuel level sending units. When I can get the check gauge light to come on and the gauge to go back to empty, I'll repeat the readings. I'm wondering if it's the stock gauge cluster that is bad. I guess if I follow the purple wire all the way to it, it should show 112 ohms. If not, something in the wiring. I haven't check the schematics yet to see which pin on the cluster is for fuel level.
HP tuners settings appear to be stock:
Capacity: 16.6 Primary Capacity: 16.8 Sender Max: 150 Sender Min: 20 Gauge uses PWM - disable PWM Gauge Frequency = 0hz Fuel Gauge Output vs Level table: 110 @ 0 up to -11.99 @ 100 Primary Volume: 0 to 256, at 256 volume is 24.30
So If I want to follow the wire to the cluster to see if it's putting out the correct 112 ohms at the given fuel level, my best option is to measure off the PCM? Looks like only one wire leading from the PCM to the DLC. Seems easier to just find another cluster and swap it in lol...
Last edited by 5.7stroker; Apr 19, 2020 at 07:34 PM.
Can the purple wires on the black power connector which are for the fuel level sending unit be swapped as indicated in the racetronix FPA-001B/RX-F99-FPA-105B instructions? I ask because on a stock untouched setup, one violet wire leads to blue PCM C1 pin 23 which is fuel level sensor ground, and the other violet wire leads to red PCM C2 pin 54 which is fuel level sensor signal.
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Fuel level sensor ohm readings 
