[C320-list] Fuel Gauge Stuck on Full

[Joe Abbagnaro]

Hi
Make sure the wires on the back of the gauge are securly attached.
One of the wires could be grounding out causing the gauge to spike to the
full
position because of a grounding condition. Check the wires on the sender
side also.

Joe


On 3/31/08, Robert E. Sloat <resloat at comcast.net> wrote:
>
> Bruce-Jeff and Chris have good advice.  I have hull 894 (2002) and my fuel
> gage got stuck on 3/4 full during the first season when the tank was less
> than that.  It turned out that the float on the fuel level sending unit in
> the tank was rubbing against the boinside of the tank so it could not go
> down
> below 3/4 full.
>
> If all else fails on your testing check out if the float is lodged against
> the inside of the tank.  One my boat you could gently tap the port side of
> the tank with your fist and hear the float rattle against the tank.  I
> removed the sending unit (it is a tight fit and you need a short phillips
> screw driver to unscrew the unit) and rotated the sending unit 90 degrees
> away from the tank and eliminated the problem.  Before removal I marked
> the
> sending unit so I would know how it was originally installed if my
> analysis
> was not correct.  This problem was noted by a fuel owners in 2002 and some
> of the fixes were what I did.
>
> I rely on the gauge reading and also use the Dobbs meter to keep track of
> engine hours and fuel usage estimates and make sure the two are close on
> fuel usage. Since I use little fuel over a season, I try to run the tank
> to
> 1/4 full at the end of the season so I can load a fresh tank of fuel
> before
> winter storage.  When I get down to the 1/4 full mark, I also measure fuel
> level by tapping on the tank with the handle of a plastic screw driver to
> locate the fuel level.  With enough practice you can discern the
> difference
> in the taping sounds above and below the fuel level.
>
>
> ----- Original Message -----
> From: "Chris Burti" <clburti at gmail.com>
> To: <C320-List at catalina320.com>
> Sent: Monday, March 31, 2008 9:23 AM
> Subject: Re: [C320-list] Fuel Gauge Stuck on Full
>
>
> > *A common problem* In this case the gauge is a voltmeter and the float
> > mechanism in the tank is essentially a variable resistor. Voltage goes
> to
> > the tank sender, if the tank is full the circuit is almost open and the
> > gauge reads full. As the float drops, resistance increases, and the
> needle
> > drops correspondingly.
> >
> > If the problem is with the sender, it can be tested by removing the
> shelf
> > in
> > the starboard aft locker and removing all wires. Tested with an ohm
> meter
> > it
> > should read between 60 and 120 ohms. Open or closed circuit readings
> > indicate a failure of the unit.
> >
> > If that checks out and, as it sounds like from your description, the
> gauge
> > reads 'full' when not working, there may be a short in the circuit.
> > If the gauge reads 'empty' when not working, there may be a broken wire.
> >
> > If the sender is good and the wiring is good, that just leaves the gauge
> > to
> > be bad. You open the engine pod to do all this testing, disconnect the
> > pink
> > power lead from the gauge, it should then read "empty". If not, it is
> bad.
> > If it does read "empty", jump the power lead from the lights to the
> > terminal
> > for the tank lead (pink) and the gauge will read 'full' when you turn
> the
> > key on. Run a jumper from the tank to the gauge, if it reads correctly,
> > you
> > have a short in your sending wire (the most common problem according to
> > the
> > techie at Seaward"
> >
> > On Mon, Mar 31, 2008 at 9:44 AM, Jeff Hare <catalina at thehares.com>
> wrote:
> >
> >> 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
> >>
> >>
> >
> >
> > --
> > Chris Burti
> > Farmville, NC
>
>