Kawasaki Fuel Gauge Fault

I think you already know the answer.

 

Latest gremlin on the GT750...

The fuel gauge has packed up - not really a problem but I can't identify
why, so many brains and all that.

It started randomly showing all manner of levels then it decided it was
empty and flashed the bottom LCD block and the red warning light flashes
(now covered with a bit of tape as it's bloody bright). It had decided
it was half full for a bit yesterday (it's got a full tank) but is now
back to utterly empty.

Here's the wiring diagram:
http://www.sweller.co.uk/docs/KawasakiGT750Diag.pdf

The sender works within spec.

What doesn't seem right is the voltage at the connector of the fuel
sender (item 38 on the diagram). I assumed the BK/Y wire is the feed to
the sender which varies the voltage and returns it via the W/Y wire to
the gauge which displays as appropriate.

The Bk/Y connection on the loom side is 0v and the W/Y connection is 5v.

I've tried connecting the sender (Bk/Y) to the battery (12v) and
connecting output from the sender to the W/Y on the loom. I expected the
gauge to show the tank level - it didn't.

It's an irritant that it doesn't work - ideas?

 

Yes, I know but I would like to fix it as the red flashing warning light
(that I've covered with tape) also warns of other disasters - value of
the bike aside.

 

look at the battery: bk/y is earth

so, it would seem that that the signal wire is held "high" when the tank is
full. As the fuel float moves it adjusts a variable resistor which will
eventually ground the signal line, as the tank empties. When that line is
grounded the red light attached to the signal line comes on (item 19).
There must be some circuitry in the LCD unit, 26, that works out the fuel
gauge reading as the voltage changes.

My diagnosis: most likely there is a short/low resistance to earth on the
signal line W/Y (assuming the splodge is a W). Of course, if you fix the
short, the pull up resistor might be burnt out or the LCD circuitry might
be fucked.

 

Is it at all possible to graft a traditional needle
guage (i.e., analogue) assembly from an earlier
GT750? That would be my preferred solution in
your position, if possible.

Then again, later analogue guages still require
the ignition on to read how much fuel is in there.

I can't see why it would need a dummy load so
one alternative is to disconnect it, take advantage
of the of extra egg-cup-full of fuel you'll be able to
fit in the tank, and leave the red LED warning light
to flash up the rest of the other warnings as and
when they may occur.

A custom tank made of glass is another way if
you're really not capable (I know you are) of doing
the mathematics involved in working out how many
miles it is since you last refuelled.

Then again, you're talking to a guy who tunes
guitars using anything from iolated piano notes in
chart music to the numeric manual input tones
on a mobile handset.

I'm going to have to find a way to coax a major
sawmill to my exhaust note.

G DAEB
COPYRIGHT (C) 2008 SIPSTON
--

 

As there was no such assembly ever fitted to any GT750, I'd say not.

 

Eh? I think you must be somewhat confused.