Gas Gauge

[pair of jacks]

The gas gauge in my 21 stays pegged at full constantly, even though I have a quarter or less tank of gas. Just started happening about two weeks ago. The boat is 10 years old. I might be the most non-mechanical person on this board- the only thing I do to my boat is wax it and fish it- everything else I gotta have someone in the know do- any theories on what has happened and is it an easy fix? Thank you.

[NoBones]

When you turn the key off does the needle stay pegged?
More then likely you have a bad ground wire on the tank.
I just went through this with mine on the 20SF.
After 19 years the ground wire corroded on the tab welded
to the tank. I had to tap the fuel gauge to get it to return to "E"

Hopefully you have an inspection port above the sender
to check it....

Good Luck, Ken

[pair of jacks]

No, when key is turned off, needle returns to E but whenever on, it reads full even when no where near it.

[Caymanboy]

Sounds to me like it has grounded out.
Disconect the ground wire from the sender, see if gauge goes back to empty, if it does good, if not, something is grounding the gauge out. then do the same with the sender wire, more than likely the sender might be bad. Install a Wema sender, more better.
OP

[NoBones]

No, when key is turned off, needle returns to E but whenever on, it reads full even when no where near it.

With that being the case, check the pink wire (should be
pink if wired correctly) It maybe shorted to ground somewhere around the tank or at the gauge it self.

See ya, Ken

[Islandtrader]

Try this:


1) Turn the key switch on, so the gauge has power.
2) Disconnect the pink wire from the back of the gauge. What does the gauge read now? If it goes from full to empty, and your fuel tank's not full, the pink sender wire is grounded out somewhere between the dash and the fuel tank sender - it may have rubbed though on a sharp edge somewhere - you'll need to try and follow the wire back to the sender.

3) Take a jumper wire (short piece of wire w/stripped ends) and jump between the pink terminal and the ground terminal (black wire). Did you gauge go to full? If so, that verifies that your gauge is working properly. If it didn't you either don't have a good ground connection to the back of the gauge (use a testlight or multimeter to verify) or your gauge needs to be replaced.

4) Get access to the sender. You should see a pink wire (the same one that's connected to the back of your gauge) connected to the center portion of the sender, and a black wire (ground) connected to the outside / screw holding the sensor in the tank.

If troubleshooting on the gauge side of things didn't answer your questions, do this:

5) With the key switch still on, disconnect the sender wire. Did you gauge drop down to empty? If so, things are working properly. If it didn't do anything, as mentioned in 2, the pink wire is shorted to ground and you'll need to trace or replace the pink wire. You can also perform a continuity check on the pink wire between the sender and gauge location.

6) Disconnect the ground wire from the sender and touch it to the pink wire on the sender. Did your fuel gauge go to full? If so, things are functioning properly. If not, the ground to the sender is bad (check with a test light or multimeter), or your pink wire has a complete break in it somewhere.

A couple shortcuts / thoughts here:

1) If you gauge reads full all the time, the pink wire is contacting ground somewhere, or your sender is so sticky it's not allowing the float to drop down when the fuel level goes down. Check the wiring side first.

2) If you gauge read empty all the time there's a break in the pink wire somewhere or the sender's stuck in the down position.

If everything checks out above, it's likely your sender.

(this came from another post)

[eggsuckindog]

that is a bad ground - I have learned way too much about gas gauges recently