[C320-list] fuel gauge repeat

[warren updike]

I go with connections too. When my gage failed the needle dropped past zero. When I called Seaward they asked me what the gage was reading and they said the gage failed. 

What follows if from 3/2008 re. the fuel gage and problems:

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
---------------------------------------------------
And this from the Google archives:
*Testing Fuel Gauges* 

 Fuel gauge is a simple ohmeter. Test as follows: 


1. Disconnect Pink Sender Wire from Gauge, and turn power ON. 
The Fuel Gauge should read ZERO Scale (< Empty) 


2. Short the Gauge Sender Terminal to Ground. 
The Gauge should read FULL Scale (> Full). 


3. Measure resistance of Pink Sender Wire to Ground. 
American Floats: 240 Ohms (Empty), 103 Ohms (½ Full), & 33 Ohms (Full) 
European Floats: 10 Ohms (Empty), 95 Ohms (Half), & 180 Ohms (Full) 
Automotive & other Float Switches may use other resistances such as 0 - 90 
Ohm, 73 - 10 Ohm, & etc. 


4. Disconnect Pink Wire from Sender on Fuel Tank. 


5. Test continuity of Pink Wire. 
Zero Ohms from Tank End to Gauge End - If not, repair or replace Wire. 


6. Measure Resistance from Sender Terminal (on Tank) to Ground on Tank. 
Should read as per (3) above - If not, replace Sender. 

---------/END/-----------------


-----Original Message-----
From: Dave Rabinowitz [mailto:windchill320 at gmail.com] 
Sent: Saturday, January 24, 2009 9:09 AM
To: C320-List at catalina320.com
Subject: Re: [C320-list] fuel gauge repeat

connections, would be my vote.  gauge seems to work, sender maybe a second
choice.  i would look at each connection for crimp integrity and lack of
corrosion,and maybe use a little bit of wd-40 on each slide
connection....you can dig more into it with a voltmeter, too....

dave
windchill
#445

On Sat, Jan 24, 2009 at 9:01 AM, james_delong <james_delong at bellsouth.net>wrote:

> I know this has been discussed before, but I am one of those over 60's with
> a case of CRS...And it's fun reading this stuff over again anyway.
>
> Fuel gauge...
>
> Worked fine until 6 months ago.  Then worked fine when it had the urge.
> When underway it would register for a time then drop to zero.
>
> Then one time I noticed it had a spasm. The needle jumped all over for 15
> seconds or so then went to zero.  No sign of life since. Died before my
> eyes.
>
> Any ideas with these symptoms?  What % chance is it the connections, %
> chance the sender, or % chance the gauge?  I'll average the responses and
> the highest % will win and I'll attack that component first!
>
> Thanks for all the votes!
>
> Jim DeLong  -  McGeeves  #453
>