Mercruiser 6.2L engine alarm problem
 

I have a 2002 Searay 270 Sundeck with a 320 hp Mercruiser 6.2L
MPI/Bravo 3 Duoprop which has just developed an engine alarm problem.

After running 10 to 15 minutes at a cruising speed of about 3400 RPM,
the engine alarm sounds. Oil pressure, oil level, engine temperature
and outdrive lubrication levels all appear to be normal. The alarm
continues to sound until idling back and shifting into neurtral.

If I run below 3100 RPM the alarm does not go off.

I have checked the engine with a digital heat gun and can find no sign
of abnormal temperatures anywhere. The serpentine belt is properly
tightened and everything else seems normal in every way.

Does anyone have any suggestions on how to troubleshoot this problem ?

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Mercruiser 6.2L engine alarm problem
 

Wayne.B wrote:
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?
Have you had to replace an impeller?

No, not yet. Why do you ask?


You really should replace an impeller every other year.

Mercruiser 6.2L engine alarm problem
 

"Wayne.B" wrote in message
...
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Have you looked at the owner's manual? Sometimes a tone code is generated to
indicate the trouble area.
Jim

Mercruiser 6.2L engine alarm problem
 

you are clueless aren't you
a tone, yukyuk

"Jim" wrote in message
ink.net...

"Wayne.B" wrote in message
...
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 16:23:40 -0400, RJSmithers
wrote:

You really should replace an impeller every other year.

The boat was taken to the Searay dealer shortly before I bought it for
the 100 hour service check. Don't know for sure but it's possible the
impeller was part of that. In any case it's my understanding that
Bravo 3 outdrives do not have an impeller in the leg like the Alphas.

I believe the Bravo 3s use an engine mounted sea water pump, not sure
it it is centrifugal or uses an impeller..

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

Wayne.B wrote:
On Sun, 11 Mar 2007 16:23:40 -0400, RJSmithers
wrote:

You really should replace an impeller every other year.

The boat was taken to the Searay dealer shortly before I bought it for
the 100 hour service check. Don't know for sure but it's possible the
impeller was part of that. In any case it's my understanding that
Bravo 3 outdrives do not have an impeller in the leg like the Alphas.

I believe the Bravo 3s use an engine mounted sea water pump, not sure
it it is centrifugal or uses an impeller..

They do use a engine mounted water pump, and it does have an impeller.
Every book and manual I have read suggests changing the impeller every
year or two. They are inexpensive and the damage caused by a broken
impeller is very expensive.

http://www.sailmag.com/boatworks/bw08.impeller.pdf

Mercruiser 6.2L engine alarm problem
 

I don't think so. The similarity between a 2002 merc i/o and your outboards
ends somewhere around the fact that they both use gas.

My first guess would be that he has the same alarm setup merc used for
years. A collection of sensors is tied to an alarm. Nothing to do with the
fuel control computer. If that is the case then he needs to determine is an
alarm sensor is malfunctioning or if one of his gauges is not working.
Probably safe to say he has oil pressure or he would have had some other
nasty symptoms by now. Overheating is the other possibility.

The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp until
it trips. Of course the shop would simply stick another sensor in and if
that didn't work you'd get charged for it anyway.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is
generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.