[C320-list] Fuel Gauge Stuck on Full

[Jeff Hare]

Hi Bruce,

  Actually, the fuel gauge circuit is very simple.  The fuel sender is
simply a variable resistor.  That's all.   
Annie's correct about the fuel sender arm.

1) If it were installed incorrectly (rotated 90 degrees like mine was) it
would not be stuck on full, instead the gauge would not be able to reach
full.
2) If it ever worked properly, then it was installed correctly, so ignore #1
3) If it stopped working suddenly and is stuck either on full or empty, then
this may indicate *either* a short or an open circuit, and I don't recall if
a "short circuit" causes the gauge to read full or empty.

* First, check the top of the tank where the fuel hoses enter and verify
that the wires connecting to the tank sender are in good shape.
* Next, remove the wheel and open the engine pod, and find the fuel gauge.  
* Ensure that the connections are in good shape.
* Follow the sender wire(s) from the back of the gauge to the "terminal
block" (where the wires come up through the tube from below).
* Frequently this junction block is a problem.  I had loose wires, and other
wires that were clamped on insulation not bare wire.

Seaward provides the tanks and gauges for Catalina and they gave me a
procedure for diagnosing the gauge many years back.  I don't have it
anymore.  Perhaps someone can find the procedure from Seaward and send it to
you, or I'll look for it if nobody steps up.

On the back of the gauge, there is a power wire and a ground wire (maybe
connected to the frames of all the gauges.)  This powers the backlighting of
the gauges.  There will be 1 or 2 other wires connected to the back of the
gauge, they go to the sender on the fuel tank.  Disconnect one of them and
then see if the gauge goes to Empty.  If it does, then it indicates (I
believe) that you probably have either bad sender.

Replacing the sender is not a big deal, but here are a few tips:

1) Try not to do this with a full tank!  The emptier the better as you'll be
able to diagnose whether it's really fixed or not.

2) Important:  Before Removing the plate on the top of the tank holding the
sender, take a black marker and make a mark on orientation of the plate and
the top of the fuel tank so that you get it oriented the same way during
reassembly.  It only fits ONE way.  Any other orientation, you'll won't be
able to get all 5 screws to align with their holes.  Close, but not quite.
Took me a while to figure out that the holes weren't symmetrically placed,
presumably to ensure that the sender goes in properly.

3) Use a Phillips screwdriver bit on a socket wrench to give you 90 degrees
access to the screws holding the cover and it's Easy.  Try a regular
screwdriver and you'll fight with it.  Don't lose the screws!

4) Note the direction that the sender arm swings when removing it.

5) Keep some rags nearby to protect against drips, clean the seal really
well before putting it back together.

-Jeff




-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Bruce Stanley
Sent: Sunday, March 30, 2008 6:42 PM
To: C320-List
Subject: [C320-list] Fuel Gauge Stuck on Full

The Fuel Gauge is Stuck on Full ... when it was 3/4 empty!

any thoughts on fixing this the problem?

thanks
Bruce Stanley #1084/FantasticLady/Sydney Australia