I changed my stock engine gauges out with gaffrig monster gauges, since I did this my temp gauges don't register. Do the gaffrig monster gauges use a special or diffrent type sending unit? I'm running Merc 454 mags carbed

I have Gaffrig gauges using all the stock merc senders and not having any problems. Maybe the sender is bad?

Dave do you have the Monster gauges or just the standard 2" gaffrig gauge?

The stock temp. sending units should work fine unless you went from the Mercury Standard of 240 degrees to the high water temp gauge of 280 degrees, in this case you will need to order the correct water temp. senders. Whoever you bought the gauges from should have mentioned this to you.

By the way, Gaffrig does not make the Monster series gauge, Livorsi Marine does...Gaffrig makes a Racing series but not the Monster series. Either way, both companies will be glad to assist you if you continue to have problems.

I hope this helps...

Don B.

I have the standard size gauges. I would guess that the internals of the gauge are the same.

Thank You guy's for the input.

Hopefully you didn't put teflon tape on the senders when you put them in the block. That can cause problem you're describing.