My fuel gauge reads empty, pretty much all the time. I thought I was just low on gas, but I put 16 gallons in to my 27 gallon tank, in which there was already some amount of gas, and it still reads empty.

The gauge occasionally bounces slightly up from E when the fuel gets sloshed around good underway. This makes me think that the gauge is ok, but the sender is wacky. Can it be adjusted, or does it have to be replaced.

I did put a new cork on the sender arm a few weeks ago, so I know it's floating!

It is easy to test the guage/sender. The sender should have one wire in the center, and one on a mounting screw. Take the center wire off, and ground it to something, such as the wire on the mounting screw. The guage should now read 'Full'. With the wire not connected to anything, the guage should read 'Empty'. This would inducate that the guage is working normally, and point to a bad sender. You obviously know how to change the sender, as you already changed the float.
Hope this helps,

You're right, that does sound easy! I'll give it a whirl tonight.

If the sender is bad, go capacitive and never change a float ever again (no moving parts).

and do use all the necessary safety precautions when working with the fuel tank, sender and associated electronics.

Check your ground.

I have 24" tall fuel tanks, where do you find capacitive senders (or any others for that matter!) for tanks that tall?

Can you install sight glasses instead? That's what a big boat like yours should have, if they are allowed with gasoline. Just make sure they have spring-loaded, normally-off valves, top and bottom.

All three tanks have senders on them--port side works fine, starboard side don't work at all (haven't done the ground test yet, but I HAVE tried a new gauge, no go--but it's the tank with a hole in it so it's empty anyway!), and the toy tank has never been hooked up to a gauge.

I don't really need sight glasses as all three tanks fill straight down from the deck, and I have a bamboo measuring stick I use for 'precision' measuring! (and using the stick is easier than lifting those steel doors anyway!)

While I'm hijacking ( ) ..

can someone (Al?) explain why I have 2 pairs of oil, volt, water temp, trim gauges and tachometers, but NO second pair of fuel gauges on the flybridge? Safety issue, electric issue...?

Centroid Products is the one I use, and they have them for Gasoline, Diesel, and water.

Available straight, or curved, up to 120" deep.

The fuel senders are available with a (standard) function that if it senses water, it immediately registers over-full as a warning.

Standard features:
A Capacitive sensor is capable of detecting water in the fuel tank. The presence of water, which will ruin a diesel engine, is readily shown by an overfull indication on the meter. If fuel were being pumped into your tank from a supplier who had water in his big tanks, the presence of the water would show up immediately on your gauge by giving a overfull indication even though the tanks were only 1/4 full. This does not damage the sensor and once the water is pumped out, everything would be normal again.
Electronics have been designed to minimize meter error caused by variation of battery voltage.

Eliminates excessive needle bounce on the meter while underway.

Can be built to fit tanks from 3 inches to 120 inches deep.

Works with most receiver units (meters).

NOTE: some VDO meters work backwards from standard meters. Please indicate if yours is this type when ordering. If you are not sure of the type you have, give us the model number when ordering please.

Update: Turns out it is the float. I checked the wiring as suggested, no problem. I pulled it out and manually moved it up an down while watching the gauge, no problem. It seems my float doesn't float well enough to pull up the arm on the sender. One piece seemed to work just fine the last time I replaced it, I guess I'll try doubling up the cork unless anyone has any better ideas for me.

Capacitive fuel level sender. No moving parts, period.

Centroid Products

You WILL have to add one 12vdc ignition-switched power wire to the boat, to power the sender.

Do not order the damped one. I did, and it normally reads very high untill it sits still quite a while. My choice was against recomendations, but I thought I knew better.
I was mistaken.

Other than my wrong choice, it is a great product. Even automatically warns of water in fuel if it senses it. Immediate overful indication, even if only partly full tank.

I have had my eye on one of theseLivorsi Fuel Sender

My question is, will the sender work with a stock guage?

Thanks for the link lowrider!

The centroids do, and you can get them to be made to work with an oddball gauge as well if you have an oddity. Just provide Centroid with the required resistance parameters.