Ls swapped 91 camaro, oil gauge not reading. I have tried the stock oil pressure sender as well as an Ls oil sender. I know oil pressure is good on the motor because I used a manual oil pressure gauge for the engine break in period. The gauge in the car does work, as well as the wire, as tested by grounding the wire out and the gauge pegging full. I am narrowing it down to possibly having 2 bad senders, possible but not likely, or maybe a ground issue when the sensor is installed in the block. When the pressure sensors are installed in the block and connected to the wire, the gauge does not move. Please advise.

 

OK... not enough information.

Does the gauge sit at the top, at the bottom, or randomly somewhere in between? What happens if you disconnect the wire? (should go to the top) What then happens if you ground the wire? (gauge should go to 0) And so on.

 

With sender installed and plugged into the connector, the gauge sits at 0, doesn't move at all when car is running. If I unplug the connecter and ground the connector the gauge pegs full.

 

That makes NO SENSE WHATSOEVER.

The OP gauge is supposed to behave as I described. Like, if you hook a gauge to an idiot light sender, which is just a switch that grounds when the pressure is too low and thereby turns the light on or opens when the pressure is satisfactory and thereby turns the light off, it will behave as I described. The temp gauge is exactly the same except opposite, since "happy" and "mad" are reversed: if you hook an idiot light SU up to that, which when it's overheated will ground the wire which would turn the light on, will make the gauge peg; and opening (disconnecting) it, which signifies "happy" to the idiot light, will make a gauge go to 0.

The way a typical automotive "gauge" works is, it has 2 coils; one has 12V across it all the time and pulls the pointer one way, and the other has the sending unit in line with it and pulls the pointer the other way according to the quantity the SU is supposed to be measuring. The location the pointer points to is thus a balance between the 2. A gauge SU, instead of being a switch, is some sort of resistance that varies somewhat linearly according to the quantity in question.

Sounds like your gauge itself is fornicated somehow, and your wiring and SU and whatnot is all OK.