Engine stalls, ignition breaker tripped- starts& stalls after 30 minutes run time -

[chaparral442]

Engine stalls, ignition breaker tripped- starts& stalls after 30 minutes run time -

Chaparrall 190SSI 4.3L mercrusier carb; 370 hours on engine - never a wrench on engine. Cruised at 3800rpm for an 1/1/2 hour running on both batteries; stopped for lunch. Changed battery to #2 ran 20 minutes, idled for 5 min then ran 15 minutes and engine shut down with electrics dead (engine dieseled and died). Turn key to start NOTHING! found ignition breaker under helm tripped , reset, started and ran for 30 minutes- engine stalled and died again. I suspected battery 2- Switched to both batteries ran for 20 minutes stalled again- went to battery 1 ran for 30 minutes no problem THEN I turned on the Stereo(with amp) and with in seconds it stalled- immediately turned stereo off and engine resumed running- Now I am thinking Alternator- Ran 40 minutes back home on battery one no electrical load and everything was fine--- I thinking change alternator and maybe both batteries as they are both a few years old-

Am I on the right track?

 

[NHGuy]

First off don't just throw parts at it. Charge up both batteries. start the motor on either one and observe the alternator gauge. If it's around 14.2 or 14.3 volts at running speeds, not just at idle. your alternator is charging. Many of the alternators in our boats have to get up to 12 or 1500 RPM to get the alternator started (excited) so that's why I said running speeds.
On the other hand if it just always runs at battery voltage you could have a dead alternator. A charged battery is 12.67 volts but it will start dropping off pretty quick once the motor is running.
Now that's not everything...you also better clean up all the battery and charge connections to shiny metal. Corrosion can wreak havoc with electrics.
If you take the batteries out you can take them to an auto parts place to test them, but you'll want them charged first. Some of the counter children don't know the difference between discharged and bad.

 

[bruceb58]

When you were switching batteries, were you doing it with the engine running and happen to switch the battery switch to off. Switch a battery switch to off while the engine is running will kill your alternator.

Measure the voltage at the batteries with a multi meter, The voltage gauge in the dash can be way off. I never trust them to be very accurate.

 

[chaparral442]

No it was not turned to the off position. I found it interesting that when I turned on the stereo with amp creating a significant amp draw the engine cut out - at once I turned off amp and stereo and engine settled down.

 

[bruceb58]

No it was not turned to the off position. I found it interesting that when I turned on the stereo with amp creating a significant amp draw the engine cut out - at once I turned off amp and stereo and engine settled down.

That is a low voltage issue. Once when I had a bad corroded connection down at my starter, my engine would die when I would use the trim. Cleanng all connections including the ground at the block is the solution for that type of issue.

You just need to get your multi meter out and see what your charging system is doing and use that info to proceed.

 

[chaparral442]

Thanks- I will start with the basics first