Having an issue with both fuel gauges always reading full. Any info. Bad grounds? 1993 42' Lightning.

Disconnect the sender. With the key in the ''on'' position, and sender wire disconnected, the gauge should be on ''e''. Now ground the wire, and gauge should peg to full. If it does, your sending units in the tanks are prob dunzo.

Just got back from the dock and that is exactly what the starboard side tank is doing. Thanks for the input MT. Now, any good idea where to order one from???

it depends on who's gauge you have? if gaffrig then you order one from then,,all the need is the legnth..

Don't laugh.

These gauges, except VDO, but gaffrigs, livorsi, autometer, etc as far as I know, use the industry standard 240/33 ohm sending units. Both mine were toast when I bought my boat in 2010. I replaced both of them with these. They are a basic float arm style. easy to install and come with directions. You just need a tape measure, and a couple hand tools. Mine are as accurate as can be. When the gauge is showing "e'', its time to get fuel. So far they been in since 2010 with no issues. No reason to spend a ton of money. 20 bucks a piece. Gaffrig gets 51.00 each for the basic float arm style like these. They worked fine with my old gaffrig gauges, and work fine with my new Autometer marine gauges. They only make 2 different types of these. Like I said, 240/33 ohm, or 90/0 which is what the very old VDO gauges used.

http://www.autozone.com/autozone/acc...ier=87625_0_0_

If it is a VDO it is probably 0-90. If it is Mercury or SW it is 240-33 ohms. You may want to look at sender also..
In Fountains the location of the sender and the way the boat sits in the water fuel gauges always look full. First half of tank takes days to empty but the second half goes quickly because there is not volume. If you change the sender you may want to consider a sender that is 2-3 inches shorter. Livorsi Marine can help you out with a sender or gauge.
We have been standard equipment in Fountains since 1996. Give us a call 847-752-2424