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I own a 1989 Camaro that was an RS V6 and is currently a carbed 355 sbc. Recently began upgrading/rebuilding the motor, and took the opportunity of a pulled motor to install a brand new wiring harness. I began by pulling almost the entirety of the old harness out, I was running into issues with degraded wiring causing the infamous intermittent issues.
After a week or two it's completely installed and I'm just chasing down one or two issues. In particular the fuel gauge. whenever I turn the key to run it just pegs above full, which after some googling I believe that implies I essentially have above 90 ohms. I could be miss interpreting that though. I'm thinking it's because I took the ground wire (black) from the 3 pin connector that passes through the body behind the rear seat, and just grounded it against the chassis/body. I'm thinking that's one of my issues.
Judging by this diagram (assuming it's correct for my application) that ground should in fact be going to the gauge. But I can't figure out which pin on the c1 or c2 connector this ground should goto.
The other issue I have (I think) is I took the fuel pump power wire from the harness and attached it to one of the wires coming from the sending unit. I may be wrong about the colors, and can verify when I get home but here's what I have spliced into the old sending unit wires:
Pink - Sending unit signal wire
Tan - 12v (fuel pump power)
Black - Grounded to chassis/frame (Pretty sure this is wrong)
Troubleshooting done so far:
-Disconnected the connector under the car and used a multimeter to measure resistance. Measured 66 ohms, and shook the car and it fluctuated. So I don't think the floats stuck.
-Pulled the fuel gauge and connected pins on back to power supply to verify it's working, although I can't find a good reference for which pins goto what. I guess the pins with the old style resister connecting them would goto the signal wire and sending unit ground. Connecting 12v pos and neg to those jumps the gauge past full. Gauge stays when power is removed.
Questions I have for y'all:
-What're the pins on the back of the fuel gauge specifically, I think the top is the ignition signal? That appears to be working correctly since the gauge will only move if ignition is turned on.
-If I'm correct in thinking the ground from the sending unit goes to the dash, which pin on the c1 or c2 connector does it run to?
-Is that 12v fuel pump power wire causing issues? Motor uses a mechanical fuel pump so I wasn't sure where else it went haha.
Let me know if there's anything I can clarify, I can take pictures later tonight if needed. Thanks!
Fuel gauge has a B+ terminal and two different ground terminals. One of the ground terminals goes to chassis. The other goes to the fuel level sender (a variable resistor) and then to chassis.
You can figure out which is which by measuring resistance between gauge terminals. B+ to chassis ground terminal is about 139 ohms. B+ to fuel sender terminal is about 61 ohm.
