Temp and Fuel Gauge don't work

AMC1320 wrote: Don't know why the noise suppressor failed, it's just a coil of fine wire, but it would not pass voltage thru it although visually it looked fine This was on a 69 Ambassador btw

Pretty interesting topic. I will add that the coil is an inductor, which DC voltage see's as 0 ohms. A noise spike sees it as high resistance. So considering voltage drop, the spike voltage gets dropped across the inductor because of it's apparent high resistance and the DC passes though uninterrupted. It sounds like the inductor opened up.

Hi Iv taken my fuel gauge out of my 78 barcelona ,

There is NO voltage on the wire that attaches to the sending unit on the tank.  Your test has proven that the gauge in the cluster is good.  You need to make sure the sending unit is grounded (earthed) with a separate wire from the body to the sending unit.  If that's good then the sending unit itself needs to be removed and repaired or replaced.

Hi I need to replace my constant voltage regulator on my 78 matador barcelona. iv taken it apart and figure the wires look dark blue and probably burnt out ok so is there a replacement or similar I can use.I checked a hundred times the resistance from the sender unit to the gauge as long as i don't run the engine its reads constant ohms at the moment after putting the sender unit back into the tank and refitting the tank to the car and putting some fuel in it reads 27 ohms at any point from the sender to the back of the fuel gauge.So i reckon the wiring is fine and the earth . ok i did take the tank and sender unit out and connect it to the gauge by using additional wires and aS i MOVED THE FLOAT THE NEEDLE ON THE GAUGE MOVED ACCORDINGLY its ranged from approx 80 ohms to 20 ohms depending i believe when the float was in the full position the gauge in ohms was max out 80 ohms and at empty approx 20 ohms so I fit the whole thing back into the tank and turn the key ..NOTHING .after swearing a lot and thinking bollocks to this I turned back to the gauge and removed the oblong tin three pronged unit known as the CVR took it apart as the thing didn't seem to work and found the contacts the wiring  the wires look like burnt dark blue and figured that's the reaSON ITS NOT WORKING ITS BURNT OUT SO i NEED A REPLACEMENT OR SIMILAR UNIT TO FIT BACK IN THE PANEL WHICH AS YOU KNOW CONTROLS THE FUEL AND THE TEMP GAUGES help PLEASE THANK YOU tONY 

Here's a link to one on the back of a 64 Classic cluster. Real easy to do, if you can solder. Either mounting method works just fine.

The original regulator is a weird little thing! It doesn't deliver a constant 5V, but an "average" of 5V. Hook a digital volt meter to a good one and it will never find a reading, bouncing between 0V and 12V. An old analog meter needle will bounce, but isn't as fast, so should hover somewhere around 12V. It's a bi-metal strip that contacts, heats up and breaks contact, cools and contacts, heats up and breaks... ad infinitum (or until it doesn't...). When it fails it breaks contact, which is good for the sending units. 12V to them all the time wouldn't be good! So between the on-off sequences the average voltage is 5V, and average is good enough for the gauges to work. They work equally well with a constant 5V, and I suspect will last longer. The old CVR and sending units last a long time though, many 40 year old units are still working, so it's hard to tell if the constant voltage makes a difference or not, but it works and is an easy fix.