Temp gauge help please?

[Deep Seeker]

Hi,

OK, so I'm new to posting on here but not new to using this lovely forum for various help with my rib. Apologies for not using the introduction part of the forum but Hi, I'm Nick, I could really do with some swift advice.

I have a 150HP Mercury V6 2-stroke outboard on my Osprey Viper (you all know the boat, it was sold to me by a fine chap who makes a bit of a project out of rebuilding these things)

I decided to make some mods and change the gauges around a bit, added a downscan sonar etc. Got a new rev counter and temp gauge from Bill Higham Marine. Unfortunately the temp gauge doesn't work at all and the rev counter worked for a couple of minutes and then just stopped. Now it sits at the 6 o'clock position when the ignition goes on.

I'll email Simon Higham in the morning but can anyone help with the following?

1) What voltage should I get from the gauge? The ignition voltage is 12.4V but the output to the sender is only 9.5V.

2) I'm assuming the temperature sender is simply a resistance change so what resistance should I get across it for the various engine temps?

3) Any ideas on why the rev counter suddenly stopped working? If it was set to the wrong pole number would that break it?

Any help on the above would be greatly appreciated. Don't want to start throwing money at gauges if I have made a boob elsewhere or simply need a new temp sender.

Thanks!
Nick

[paintman]

First question is have you tried reconnecting the original gauges & if so, do they work as usual?
If they do then the issue is with the new bits which could be incompatible, defective, incorrectly fitted (with electrical items the last can result in them being damaged)

[Nightfisher]

Did you change-out the sender unit too? Some sender units mounted near or on the water manifold are not compatible with non-original gauges. Good luck.

[Deep Seeker]

Thanks guys. Not sure what was wrong with the rev counter in the end so it's just sitting on my desk and now I have a proper mercury tacho fitted which works well.

The temp gauge was indeed the sender. Took me a while to work out that a V6 Merc has a switch on one block and a sender on the other but they are a contact type rather than an immersion so my gauge is showing something other than cold which will do for the time being. The merc parts list online doesn't tie up the sender with the gauge so I've still to sort that out as it's not using the whole of the range.

Now I've just to work out why my VHF gets interference from the engine and why my spark plugs are always wet.... boats eh...?

Cheers
Nick