Mercruiser Alpha 1 - backfired and died out on the water ( Its electrical 100% ) - need basic troubleshooting steps,, how do i check charging system?

[chatvmax]

Boat sat for a full year -
- Charged battery to ( full ) on my charger, checked all fluids and she started fine,
let her warm up and we were off -
- ran about a full hour at 3500 rpms real strong,,
- shut her off for about 20 minutes while we talked and hung out
- started fine and strong
- ran about another 20 minutes , always checking temp , oil pressure - great , also the voltage gauge was about 12v,
- was running along about 3000 rpms and she started to miss about amd backfire,
- i quickly swithed gas over to second tank and missing continued about another 10 seconds , then a loud backfire and she died
- i then tried to start and the battery acted stone dead, i could hear the started crank a second then click, the horn beeped and the trim still worked and the voltage was reading 12v ( normally about 14v )
- got home and put a meter straight on the battery while disconnected from boat and it was 13v
- put the battery charger on the battery ( isolated from boat and it is pulling a full 16 amps while charging,, usually 3 amps or so is normal..
- next steps ????
how can i check to see if the charging system is working ??

 

[nola mike]

how can i check to see if the charging system is working ??

Check the voltage at the battery while running. Should be around 14.7v or so.

 

[chatvmax]

Check the voltage at the battery while running. Should be around 14.7v or so.

ill charge battery and tomorrow ill run it with a fully charged battery,,,
and are there any test points to check that regulator or stater

 

[nola mike]

ill charge battery and tomorrow ill run it with a fully charged battery,,,
and are there any test points to check that regulator or stater

Stator? Is this a 470? Start at the battery. The stator doesn't usually go bad, but if you have a regulator still it's had a good run

 

[alldodge]

got home and put a meter straight on the battery while disconnected from boat and it was 13v

Is this a AGM Bat?

 

[chatvmax]

Is this a AGM Bat? - iv included a pic of the battery, - not sure about AGM,

battery when i pulled it last night when i got ome,, it " acted " so drained it cranked the boat over very slow then clicked,
13vdc last night,
then i hooked the charger on and it registered 16 amps charging ,,, wow,,
- this morning the charger indicated Full charge,,
so i measured voltage and i got 12.9vdc ,,, what the hell,,
, so i disconnected charger and let it all sit an hour and reconnected charger and it indicated .2 amp charge and Full charge,, ( at 12.9vac )
- i also checked individual cells ( left to right ) and got the following,
2.2vdc , 2.2vdc, 2.4vdc, 2.3vdc, and 2.3vdc , across the cells,
- this is a alpha 1 merc with a original stator and voltage regulator -
((( this morning i hooked mg Good battery from my car and it cranked slow but wanted to start - didnt have water to her so i did not start -
next step may be start her with water and good battery and make measurements - any suggestions -

 

[Scott06]

- this is a alpha 1 merc with a original stator and voltage regulator -

View attachment 385753

So this is a 3.7 or 470 with a stator and voltage regulator?

Would suspect stator or more likely regulator issues in which case given NLA nature of these parts would do an alternator conversion and replace the battery.

Would target your trouble shooting around the odd ball charging system this engine has, may need to sub in a new battery to diagnose.

 

[chatvmax]

Stator? Is this a 470? Start at the battery. The stator doesn't usually go bad, but if you have a regulator still it's had a good run

hello,,,
deeply appreciate the help,,
fell free to peek down the thread as i just answered someone on type of battery and i included how the battery is acting,,
- it is a 3.7 ,
- that was also to say its the original stator - and water cooled voltage regulator,
- also cranked rather slow this morning with a fully charged car battery and the fully charged original battery,,,
- i wants to start but did not have water to her so did not start,,,
- next steps -to start and make measurements ....?
- so if i leave the new battery in there are there voltages im looking for off the stator , and then the down stream side of the voltage regulator...?
- - could the starter be sucking all juice down when hot..? and then just cranking slow when cold..?
- is it a huge job to get that starter out for measurements or inspection...?

 

[Dubed]

I would pressure test the coolant system and make sure your not ingesting water. Could explain the slow crank and could have bent a pushrod or other damage. These motors are well known for it.
Then ****-can that 40 year old voltage regulator and install an alternator conversion kit. My opinion

 

[alldodge]

battery when i pulled it last night when i got ome,, it " acted " so drained it cranked the boat over very slow then clicked,
13vdc last night,
then i hooked the charger on and it registered 16 amps charging ,,, wow,,
- this morning the charger indicated Full charge,,
so i measured voltage and i got 12.9vdc ,,, what the hell,,
, so i disconnected charger and let it all sit an hour and reconnected charger and it indicated .2 amp charge and Full charge,, ( at 12.9vac )
- i also checked individual cells ( left to right ) and got the following,
2.2vdc , 2.2vdc, 2.4vdc, 2.3vdc, and 2.3vdc , across the cells,
- this is a alpha 1 merc with a original stator and voltage regulator -
((( this morning i hooked mg Good battery from my car and it cranked slow but wanted to start - didnt have water to her so i did not start -
next step may be start her with water and good battery and make measurements - any suggestions -

That's a standard deep cycle lead acid and full charge should be 12.7V
Your higher readings just means your meter is off a little. No biggy just something to note

 

[QBhoy]

Hi. Not making much sense of the battery charge thinking there..but anyway, if there is any doubt over the battery, replace it.
When she’s running, you should be seeing at least 13.5 volts and ideally more.
Finally, hope I’m wrong…but you’ll no doubt be aware that the notorious 3.7 has a party trick or two and of a bad habit, of her water pump failing..resulting in a very quick overheating situation without warning (unless you noticed the pump weeping). Shortly after or during this…the occurrence results in a warp of the head and/or a loss of sealing ability between the head and the dissimilar metal of the block. All too easily I’m afraid. From then on in…it’s a world of endless failed repair, rebuilding and never being trusted again. Takes a real patient and rigorously stubborn fella to endure and persist in the upkeep these things demand.