MerCruiser 8.2 big block 2014 — shuts off after 5-7 min of running

[BobDiP]

Recently purchased a 2014 SeaRay that has an 8.2 MAG - Big Block V8. We got it into the water today and it started right up, after 5 min or so it shuts off immediately without warning.

Once it cuts out it will not turn over for 10-15 min, but the batteries are pulling 12V so they have plenty of power to start.

At a complete loss. See attached video

 

[alldodge]

will not turn over

Clarify your term. For me it means the motor will not crank, so not turning over. Others use the term it cranks but will not start?

If it does crank but not start. Do you get 2 beeps when the key is turned ON (run) before it cranks?

 

[BobDiP]

Clarify your term. For me it means the motor will not crank, so not turning over. Others use the term it cranks but will not start?

If it does crank but not start. Do you get 2 beeps when the key is turned ON (run) before it cranks?

It does not crack over, When turning the key nothing happens, not noise at all. It's almost as if there is a safety switch causing the engine to shut off and until it resets or cools down it wont do anything.

 

[alldodge]

Thanks, were on same page
Need a motor serial number and if the boat has digital controls or cable

When it won't crank, check the 50 amp breaker on the motor. It should have 12V on both sides. If it has it only on one side then the breaker is disconnecting. The breaker will reset when it cools down

If it does have 12V on both sides, see if its on the red/purple wire at the ignition switch

 

[BobDiP]

Thanks, were on same page
Need a motor serial number and if the boat has digital controls or cable

When it won't crank, check the 50 amp breaker on the motor. It should have 12V on both sides. If it has it only on one side then the breaker is disconnecting. The breaker will reset when it cools down

If it does have 12V on both sides, see if its on the red/purple wire at the ignition switch

Awesome I will check that and take some photos to make sure I am looking in the correct area. Will report back.

 

[BobDiP]

Awesome I will check that and take some photos to make sure I am looking in the correct area. Will report back.

Here are the engine numbers.

 

[alldodge]

Thanks 2A195012 list 8.2 HO

 

[BobDiP]

That’s correct

 

[BobDiP]

Thanks 2A195012 list 8.2 HO

 

[BobDiP]

have to head back down to the boat to check fluid levels, but if this something that could result from low engine coolant levels? Or low oil levels?
Being there are no warning alarms going off I feel it’s a safety feature that’s saying somethings getting to hot “I” need to cool down a bit before running again

 

[alldodge]

If your low on oil there would be an alarm and a code
If coolant is low but not to low it may be a non-issue

Have you check to see if power is at the 50 amp breaker when motor stops?

 

[tank1949]

Did you examine all terminals for corrosion? Boats love the crap!

 

[Scott06]

have to head back down to the boat to check fluid levels, but if this something that could result from low engine coolant levels? Or low oil levels?
Being there are no warning alarms going off I feel it’s a safety feature that’s saying somethings getting to hot “I” need to cool down a bit before running again

I would agree with AD you are loosing the 12 v run power intremittently, the only thing getting hit may be the breaker as mentioned. Do yoiu have power at the helm when this happens? You will need to trace this out to and from the key with a voltmeter

 

[BobDiP]

UPDATE:


Discovered something new today. It appears to be an electrical issue because when the engine cuts off we’re able to shut the battery off and turn it back on and start it right up.

There are no alarms or warnings at the helm and it also loses power when the motor cuts out. We load tested both batteries and they’re both good. The voltage on them doesn’t dip or drop off when the motor cuts out

 

[alldodge]

Breaker voltage?

 

[BobDiP]

The Mercury smart craft we have is displaying the temperature at -27F which I’m being told is the default for a faulty sensor.
Could this be triggering the engine to shut off by chance? If so anyone know where this sensor is located as I’ve combed the manual 5x and can’t find it

 

[alldodge]

Most the time its on the thermostat housing. Its probably reading that because of a voltage issue. Other sensors are probably doing the same.

 

[BobDiP]

UPDATE:
So we’ve had a decent amount of time now to go through fuses, breakers, sensors, etc. and we’ve determined that the one of the batteries isn’t charging when the engine runs. So as a result the engine is slowly draining it; causing the motor to shut down.
Any suggestions on where or what to do next? It’s not the alternator because the other batter is charging and we switched the batteries around to see if it may have been the battery (despite them both loading good) and it didn’t matter which battery was where it was the same #2 location that would not charge.

 

[alldodge]

Does the charging system use an isolator or ACR?

Start motor and measure voltage at the ALT and each Bat. Find the connection between ALT and non-charging Bat

Otherwise remove cables and clean real good to shinny metal.

 

[Lou C]

If you can run it on the battery that does accept a charge, and see if it does not cut out then.
When it dies have you seen the voltmeter dropping?