gas gauge ground?

[another best/worst day]

I recently had my motor go into alarm mode (no sound). I found some corroded wires in my transom (1990 Yamaha 70 hp) and noticed a wire from the gas gauge to the bolts on the motor mount. Is that correct? I didn't know you grounded wires in a DC system.

[fairdeal]

sounds like a hacker was at work.

on the engine, the negative battery cable bolts to the block -
so there may be various places on the engine
where ground is made by attaching a wire to the block.

But inside the boat,
grounds for circuits carrying 'power' should be made by going back to the battery negative -
not a bunch of individual 'home runs' of course -
but via one or more 'negative bus' connections.

So the ground for the gas gauge should go to such a negative bus -
or back to the gauge's ground connection.
Not to the engine mounting bolts.

Now there are other 'grounding' situations on a boat,
but which are not completing a power circuit.
They are generally distinguished by calling them "bonding"

One important one is a wire connecting all metal parts of the fuel tank system -
so from the metal filler cap, to the tank itself.
This is to prevent a spark from a static buildup.

And there is a tradition - not universally applied -
to have all metal parts of the boat which are in contact with the water -
through-hulls, props, rudders, shafts and sacrificial anodes -
'bonded' by wire inside the boat to minimize corrosion from galvanic action.

Yamaha applies this principle to the engine -
there are usually several small stainless steel cables
connecting the parts of the bracket and lower unit -
to ensure that everything is in electrical contact with the anodes.

[another best/worst day]

Fairdeal,

Thank you for the response. I didn't think that was normal to ground the gauge either. And you hit it out of the park regarding a prior owner "hacker." I have a bit of a wiring nightmare on my hands. He decided to put a "house" battery under the steering column and he rewired the bilge pump and livewell pump to that battery along with the new electric *****ing motor he purchased. He also has the lights and auxilaries going to that battery. The only thing on the engine battery is the engine. The start of my problems was that he put in an automatic charging relay for both batteries and I "ate" two new batteries before I realized the relay system was shorted out. Oh well...you buy used you get what you get!

[another best/worst day]

Is "*****ing motor" a bad word on this forum?

[fairdeal]

apparently the software package used here
has some features to discourage spam and other posts from bots
and perhaps, impolite words

its blocks the name of a precious metal
(I recall back in the day the internet was awash in spam posts selling "gold")

not clear to me why it blocks the mythical creature who lives under a bridge -
of course that's also the word for a troublesome non-serious poster

[fairdeal]

interesting.
I thought we couldn't say "gold" here.

[boscoe99]

I wonder if it is the quotation marks used for gold.

[boscoe99]

Nope. It is not. Things change.

I used to not be able to say Rube Goldberg.

[another best/worst day]

Another question...

I can get a picture of it tonight but there is a small gauge wire (broken and corroded) hanging off of motor - between the motor and prop. It is about 6" long. I just can't seem to find where this may have gone to??? Would this connect to the anode bar on the motor mount?

[another best/worst day]

Is "*****ing motor" a bad word on this forum?

I guess I'll just call it a trelling motor?

[fairdeal]

.. there is a small gauge wire (broken and corroded) hanging off of motor - between the motor and prop. It is about 6" long. I just can't seem to find where this may have gone to??? Would this connect to the anode bar on the motor mount?

Sounds like a bonding wire I mentioned earlier - perhaps #62 in the diagram below -
which seems to go from the lower motor mount to the bracket -
although that doesn't seem possible...

Yamaha's documentation of those wires is generally poor - and these older diagrams are atrocious

[TownsendsFJR1300]

Use the number ZERO when typing anything with Tro0l

[another best/worst day]

Took a pic this morning. Not sure if this helps...