ISPKI

Here is where I am getting kind of confused. I have been told that there is a temp sender and a temp sensor. The sensor sends a signal to the ECU, the sender sends a signal to the gauge. Reading the manual, it does not say that it has a sender and a sensor, it says that what I thought was the sender for the gauge is the thermotime switch for the cold start valve. So where does the gauge get it's information from?

Howdy folks, first post here. I have this same thread running on a couple other sights but havent gotten a whole lot of responses. I have a 1977 280z - that is fuel injected. The vehicle was not maintained well by the previous owners and I am restoring it. At the top of my repair list is the coolant temperature. The needle on the gauge moves to the middle of the gauge when the key is turned to on (or the vehicle is turned on) regardless of whether or not the engine is cold or hot. The needle sits there and does not move from the center of the gauge. This has led me to look at the coolant temperature sensor and senders. I was told that if you ground one of the wires for the coolant temp sender, then the gauge should move to the HOT end and stay there. However, regardless of which wire I ground, the gauge returns to the same spot, right in the middle. I then removed the gauge to check and make sure that it was not jammed, which it was not. As far as I know, there is nothing else on the cercuit between the sender unit and the gauge so what could cause the gauge to not be reading correctly. I tried testing the system with a meter but I can barely get a reading and when I do the reading is rarely consistent. The only consistent reading I got was 512 with the meter set to 20k. The reason I am trying to fix the gauge is because the vehicle slowly develops a rough idle as it warms up and will eventually become so rough that it will not even drive up a hill. There are many other issues that need fixing as well; The fuel pump does not prime the fuel system when the key is turned to "on". The fuel system drains out when the car is turned off.