My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and set
aside, etc.). I just started up the engine for the upcoming season and the
new tach is fine. However now I have a new issue with the temp gauge. Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running. That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of the 2
old tach wires for the new tach to connect to "w"? No other wiring changed
from the time the temp gauge was OK. Ideas welcomed.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://home.comcast.net/~kerrydeare

On 06/04/2010 21:04, Armond Perretta wrote:
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and set
aside, etc.). I just started up the engine for the upcoming season and the
new tach is fine. However now I have a new issue with the temp gauge. Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running. That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of the 2
old tach wires for the new tach to connect to "w"? No other wiring changed
from the time the temp gauge was OK. Ideas welcomed.


Check for voltage drops between various earth points when the alternator
is charging.

On 06/04/2010 21:33, goofball_star_dot_etal wrote:
On 06/04/2010 21:04, Armond Perretta wrote:
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was
fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and
set
aside, etc.). I just started up the engine for the upcoming season and
the
new tach is fine. However now I have a new issue with the temp gauge.
Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including
the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp
gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running.
That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of
the 2
old tach wires for the new tach to connect to "w"? No other wiring
changed
from the time the temp gauge was OK. Ideas welcomed.


Check for voltage drops between various earth points when the alternator
is charging.

In particular, check the integrity of the alternator earth path (since
it seems that the error is associated with charging current), the engine
earth path (since, probably, the temperature sensor thermistor uses the
engine as earth), and the instrument earth (since that is where you see
the problem). In an ideal world one would have a single point earth but
this is not always practical.

It is absolutely essential that DC return is isolated from the hull. There is no such thing as not practical. Failure here with
induce electrolytic corrosion throughout your boat as well as neighboring boats at your marina. There have been multiple threads
here on this very subject. Engine installations are the number one source of this fault by amateurs and professionals alike. Boats
are not automobiles and must not be wired in the same manner. The general cause is that many of these engine sensors use the
engine block as the DC return.
Steve

"goofball_star_dot_etal" wrote in message o.uk...
On 06/04/2010 21:33, goofball_star_dot_etal wrote:

In particular, check the integrity of the alternator earth path (since it seems that the error is associated with charging
current), the engine earth path (since, probably, the temperature sensor thermistor uses the engine as earth), and the
instrument earth (since that is where you see the problem). In an ideal world one would have a single point earth but this is
not always practical.

On Tue, 06 Apr 2010 23:49:41 +0100, goofball_star_dot_etal
wrote:

On 06/04/2010 21:33, goofball_star_dot_etal wrote:
On 06/04/2010 21:04, Armond Perretta wrote:
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was
fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and
set
aside, etc.). I just started up the engine for the upcoming season and
the
new tach is fine. However now I have a new issue with the temp gauge.
Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including
the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp
gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running.
That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of
the 2
old tach wires for the new tach to connect to "w"? No other wiring
changed
from the time the temp gauge was OK. Ideas welcomed.


Check for voltage drops between various earth points when the alternator
is charging.

In particular, check the integrity of the alternator earth path (since
it seems that the error is associated with charging current), the engine
earth path (since, probably, the temperature sensor thermistor uses the
engine as earth), and the instrument earth (since that is where you see
the problem). In an ideal world one would have a single point earth but
this is not always practical.

I'm a bit confused. Assuming a normal inboard engine installation, the
alternator earth is normally either through the case to the engine
block or through a separate earth connection to the same place. The
engine is normally grounded/earthed by a direct connection back to the
negative side of the battery.

It almost has to be connected this way as the starter, which IS
earthed through its case to the engine block will never develop its
normal power without an adequate earth/ground path back to the power
source; the battery.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On 07/04/2010 14:14, Bruce wrote:
On Tue, 06 Apr 2010 23:49:41 +0100, goofball_star_dot_etal
wrote:

On 06/04/2010 21:33, goofball_star_dot_etal wrote:
On 06/04/2010 21:04, Armond Perretta wrote:
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was
fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and
set
aside, etc.). I just started up the engine for the upcoming season and
the
new tach is fine. However now I have a new issue with the temp gauge.
Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including
the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp
gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running.
That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of
the 2
old tach wires for the new tach to connect to "w"? No other wiring
changed
from the time the temp gauge was OK. Ideas welcomed.


Check for voltage drops between various earth points when the alternator
is charging.

In particular, check the integrity of the alternator earth path (since
it seems that the error is associated with charging current), the engine
earth path (since, probably, the temperature sensor thermistor uses the
engine as earth), and the instrument earth (since that is where you see
the problem). In an ideal world one would have a single point earth but
this is not always practical.

I'm a bit confused. Assuming a normal inboard engine installation, the
alternator earth is normally either through the case to the engine
block or through a separate earth connection to the same place. The
engine is normally grounded/earthed by a direct connection back to the
negative side of the battery.

It almost has to be connected this way as the starter, which IS
earthed through its case to the engine block will never develop its
normal power without an adequate earth/ground path back to the power
source; the battery.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Fortunately the starter is not running, so does effectively does not
exist during normal operations. I bet some meters kick when the starter
is operated on many boats..
There comes a point when it is quicker to get a meter out and fix the
problem rather than to speculate what should be, or might be. It stinks
of a 'common mode' problem to me, and I would check the earth conections
first. I look forward to hearing the result.

On Wed, 07 Apr 2010 14:59:02 +0100, goofball_star_dot_etal
wrote:

On 07/04/2010 14:14, Bruce wrote:
On Tue, 06 Apr 2010 23:49:41 +0100, goofball_star_dot_etal
wrote:

On 06/04/2010 21:33, goofball_star_dot_etal wrote:
On 06/04/2010 21:04, Armond Perretta wrote:
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was
fine
with all gauges except the tach performing properly. I have replaced the
original tach with the latest (both wires removed from the old sender and
one of these to "w" on the alternator, the hour meter wire removed and
set
aside, etc.). I just started up the engine for the upcoming season and
the
new tach is fine. However now I have a new issue with the temp gauge.
Here
are the symptoms.

Prior to starting, when I turn the key one click, all gauges including
the
temp move a bit, indicating that the wiring is fine to all instruments.
Nothing happens with the tach of course. When I then start up, all gauges
including the new tach perform as designed, except that the old temp
gauge
(which ran perfectly last year) pegs to the left once the engine starts,
giving what looks like reverse polarity connection symptoms. I did not
change any wiring to this gauge when fitting the new tach.

Next, when I shut down after running the engine under load and letting it
come to temp, all the gauges including the temp show what appear to be
correct readings, but only when the engine is NOT actually running.
That is,
it seems the temp sender is OK and sending correct info, the oil sender
same, the voltage meter same, the tack off of course, etc. I think this
means the temp sender is fine, but that running the engine is somehow
sending the incorrect voltage to the meter. Only when I start up and the
engine is actually running (and the tach showing the revs) does the temp
gauge peg to the left. Is it possible I just picked the wrong one of
the 2
old tach wires for the new tach to connect to "w"? No other wiring
changed
from the time the temp gauge was OK. Ideas welcomed.


Check for voltage drops between various earth points when the alternator
is charging.

In particular, check the integrity of the alternator earth path (since
it seems that the error is associated with charging current), the engine
earth path (since, probably, the temperature sensor thermistor uses the
engine as earth), and the instrument earth (since that is where you see
the problem). In an ideal world one would have a single point earth but
this is not always practical.

I'm a bit confused. Assuming a normal inboard engine installation, the
alternator earth is normally either through the case to the engine
block or through a separate earth connection to the same place. The
engine is normally grounded/earthed by a direct connection back to the
negative side of the battery.

It almost has to be connected this way as the starter, which IS
earthed through its case to the engine block will never develop its
normal power without an adequate earth/ground path back to the power
source; the battery.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Fortunately the starter is not running, so does effectively does not
exist during normal operations. I bet some meters kick when the starter
is operated on many boats..
There comes a point when it is quicker to get a meter out and fix the
problem rather than to speculate what should be, or might be. It stinks
of a 'common mode' problem to me, and I would check the earth conections
first. I look forward to hearing the result.

I was commenting on the remark about multiple ground circuits, as
there aren't any. The Temp and pressure senders are grounded through
their case to the engine block. The alternator is grounded through its
case to the engine block.The starter is grounded through its case to
the engine block. If an electrical ignition engine the ignition is
grounded to the engine block. The engine block is grounded through a
big cable to the battery Neg. post. No multiple paths.

As far as the instrument problem is concerned the logical plan would
be to undo the last thing done, i.e., disconnect the Tach and see what
happens?

Hardly rocket science but if only one thing changes - the bloke
connects a different tachometer - and all the instruments fail then
????.
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)