1999 penta 3.0 gs temp gauge not reading. Temp sender tested ok. How test gauge?

[paulandavolvo]

Hello all. I appreciate the help here. I'll keep it brief.
With key in "run" grounded out temp sender post, temp gauge reads null
Pulled sender off the manifold block immersed in 165 degree water for 2 min, pulled /dried placed on counter. Tracked resistance starting at 0.185 ohms up to 0.400+ as unit cooled to room temp. Read from top post to thread body w/ unit dry.
Double checked all accesable connections including temp gauge.

I'm confident sender is good. How can I test the gauge before tearing into the wiring?

 

[Augoose]

If I were you, I'd purchase a replacement Faria or Teleflex temp gauge for $30 and swap it to see if it works.
However, a quick search turned up the following...

Taken from Teleflex's website...

1. To test gauge, voltage from "I" to "G" terminals must be 10-16 VDC. No wire on "S" terminal. Gauge pointer should rest below 120. Next, connect the "S" terminal to the "G" terminal (leave "I" and "G" terminals connected). The gauge pointer should rest above 240.
2. The resistance of the sender can be measured to determine the sender's correct operation. Remove wire to gauge. Connect an ohmmeter to terminal of sender and to engine block. Approximate values are: 75 (room temperature) = 600 to 800 ohms; 212 degrees = 55 ohms.
3. If sender is shorted (0 ohms) gauge will read above 240F.
4. If sender has infinite resistance (Open) gauge will read below 120F.

I couldn't locate Faria instructions but hopefully this will get you going.

 

[paulandavolvo]

Thanks for the suggestion! At only $30 I might just bite the bullet and swap out the gauge. Do you have any suggestions on cross referencing the part number? Asking as from your post it seems like you've gone this route before.

 

[Augoose]

Post up the make and part number you find and it should be fairly easy to locate an equivalent. And yes, my fuel gauge was acting wonky in the past- rather than pour a lot of time into trouble shooting, I just replaced the gauge and that was it!