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Coil, voltage reg or Alternator

Forbin

Member
I slowley figuring out what the problem is with my boat. My assumption now is that it is electrical. Here is what it does:

Boat start perfect and out of the marina it rides like a new boat. I can slow down and get back to WOT a bunch of times. I have had the boat out 4 times this year. Everytime it runs perfect for 20 to 30 min then....I turn it of and fish or relax abnd then when i start it up it turns to crap. struggles to plane or move fast and crawls back to marina. Everytime same thing. If I start it up now I bet it would run perfect for first 20 until I shut it of and let it sit.

When it is running perfert the the battery guage show between 12 and 13 volts. When I start it up after sitting and the boat is really struggling then the battery guage shows oly about 10 or 11.

Please help with diagnosis.​
 
you should be getting over 14 when running.

Take the alt to any auto zone have it tested. If bad post back before you buy anything.
 
Ok I will do that but you don't think it might be the coil? It may even get up to 14 when it is riding good. All I know is that when I am struggling back to the marina it is at 10 or 11 (in the red). I will get back.
 
No suggestions?

You did NOT state WHAT engine we're diagnosing here. Year? Make? Drive System? Boat it's in?

I would start by removing the Alternator, AND Voltage Regulator and having both tested. If they are OK, then test the coil. It could be " overheating", and breaking down. Take it from someone whos been there, done that. If you have points, take a look at them, and do a Gap/Dwell check. My Boat has a 225 Buick V6, and I had similar problems. It has points.
 
coil doesn't pull enough current to affect the whole system's voltage.
...alternator can maintain 14.5V all day even if the coil is dead shorted.
It would blow the ignition fuse long before it ever affected the system voltage

sounds like a bad battery or starter cable connection or ground connection at the block, or the excitation circuit for the alternator
or the alternator
 
Last edited:
Figured it out. The 1976 Crestliner 165 OMC straight six ha s2 batteries. One was completely dead and the other was fine but the alternator was junk. Finally after 3 weeks of diagnosing and with everyones help from this sight I have found the culprit.

One question: DO I need 2 batteries or is one fine. It is set up for 2 where both are connected. I guess I will get my alternator rebuilt.
 
Ok Folks I am back and frustrated! I checked and got the fuel system checked out. Then I found out the electrical was an issue. One battery was dead and Alternator was garbage which also ruined the voltage regulator. I changedand fixed all that thinking I am out of the woods but here is whats hppening now:

Boat again starts great out of the gates. Cruizing for 20 minutes then stop and turn the motor off. When I turned the motor of I noticed a blackish fuel floating around the back of the boat. Sit in the water for about 30 min. When I start the boat is feel like crap and agian struggles to get up on plane. Smell a bit of gas. It just struggles and struggles. When I go to neutral it quits. When I want to start it I have to give it gas or it will just keep turning over and over. Then is struggles to get up on plane. Same old story. Is it my carb? My voltage in the boat is a good 14v. What does it start out great and then turn to garbage. I thought the coil but my electrical seems good. Is it the carb or something I don't know about. Help! I am at my wits end.​
 
fuel pump test 4-7 psi no less no more. If good then the float in the carb may not be floating anymore. Or the needle seat is shot or both.

Rebuild the carb. Do it before you run it anymore.

You have fuel getting pass the needle and going into the mani. Reason is above.
 
one bad or going bad battery can and will pull down a good battery.

I forget did i say to get it running good on one battery then add a switch and another if you want to.
 
Ok so my do I need to rebuild the carb if it may only be a choke issue. Becaus eliek I said 100 times it runs great out of the gate. Then when I stop for a bit and start up again it is sluggish and a black carbon mixture is coming from exhaust. Would that be un spent fuel? Does that me my choke may be stuck? Can I fix that with out rebuilding my carb. If it was a rebuild issues wouldn't it always run crappy?
So fix choke problem or rebuild carb?
 
I know how to adjust the choke but what are those 2 adjustment screws on the bottom of the carb? What do they do and how do I know which one does what?
 
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