temp gauge

[lostinboat]

Hi, I have a 1994 mercury 75hp. I have installed a new temp gauge with sending unit. problem is it's not working. ohms at sending unit is within specs. 16g wire running from sending unit to gauge and hooked up to the "s" terminal. 16g wire hooked up to the purple wire from ign switch and hooked to " I " terminal so hot with key on and motor running. 16 g wire running to ground and hooked to ground terminal. why is it not working ??? this is driving me crazy..... thanks for any help..

 

[merc850]

Re: temp gauge

I just installed one today and used a heat gun to test, worked fine. Is the engine getting hot enough? Take sender out and connect threads section to ground then apply some heat, if no reading then maybe gage is defective.
There is a warning on gage to not connect the (S) to + or you'll fry instrument.

 

[lostinboat]

Re: temp gauge

sending unit is attached to the head by head bold. is a surface mount sending unit.

 

[Silvertip]

Re: temp gauge

The shell of the sender must be grounded as well and it should be since the bracket is under a head bolt. However, the tip of the sender must be in firm contact with the head and as close to the spark plug as possible. Is the gauge calibrated C-N-H or does it have numbers? Teleflex made a change in their gauges and the proper sender must be used. Instructions are on their web site. As for wiring, "verify" that you have +12 volts and ground on the gauge. Looking is not verifying -- measure it. Verify that the terminal installation on the wires is crimped properly.

 

[lostinboat]

Re: temp gauge

temp gauge is now working. problem was paint on bottom of head bolt and top of head too. My dumd a** forget to clean them before installing.Thanks for the help... some days i can just be dumb. Thanks