Alternator Problem

[boatuser99]

Hi,

I have a 2003 Mecruiser 4.3 Alpha One Stern Drive. What is happening is that at low RPM, the radio is dropping out (i.e. shutting off). When the RPM's get higher, the radio returns.

When the engine is at a low idle, the gauge that displays the charge is low. When I increase the RPM's, then the needle increases (for lack of a better word).

Is this an issue with the Alternator? Wiring? I don't think it's the battery, as the radio works when the engine is off and is running solely off of the battery.

Thanks,

Boatuser99

 

[libellav15]

Re: Alternator Problem

hi bud

the ammeter reads higher when not at idle as the alternator is linked to engine speed - via drive belt - and as the rpm's increase the alternator puts out higher charge/amps/volts - so thats normal

is the radio actually losing power - and going off - if so check wiring connections for tightness/corrosion etc

or is it still powered on - just losing reception - you might need a suppressor to cure interference at idle

good luck

adam

 

[Doernuth]

Re: Alternator Problem

Check the wiring. also use a meter to measure the output of the alternator. It almost sounds like a voltage regulator problem. The regulator is most likely built into the alternator.

 

[boatuser99]

Re: Alternator Problem

The radio is actually shutting off - the display on the radio actually disappears.

I guess I don't understand wiring/radio's - to me (someone who doesn't know much about electric currents, etc), the alternator isn't generating enough current to keep the radio going -

 

[libellav15]

Re: Alternator Problem

the radio works with engine off - so there is obviously enough charge in the battery alone to run the radio - so it isn't relying on the output from the alternator.

voltage regulator? good call maybe.

try turning something else on - say running lights - do they go off at the same time as the radio goes down - and again come on when the revs increase and the radio comes back on?

if not it can't be the voltage regulator -

also if it was the voltage regulator shutting the system down it would also shut down the ignition system and cut the boat out.

if it were me i would try running power directly to the pos and neg of the radio and see if it still goes off at idle.

 

[boatuser99]

Re: Alternator Problem

If I turn my blower on with the RPM's low, the Radio will turn off. As I turn the blower off, the radio comes back on.

To me, there just isn't enough current.

 

[libellav15]

Re: Alternator Problem

you either have a mighty powerful stereo - or a crossed wire somewhere

again if it were low on charge the blower would go off as well - if you see what i mean.

trace the wiring back completely from the stereo to find the short circuit - it needs doing as misplaced sparks on a boat can be disastorous

 

[boatuser99]

Re: Alternator Problem

First of all, I'd like to thank you for all of your responses. I figured it would take a couple of days to get a response, and you have provided many in a span of an hour or so,


Just one more detail, hopefully to make things more clear. When the boat is running - i.e. moving at a decent speed, the blower can be on, along with the radio and I can toot the horn, all at the same time, with no degradation in performance (sometimes i forget to turn the blower off, and it runs while I am underway.)

Do you still think it is wiring issue? Clearly, you know what you are talking about. http://forums.iboats.com/images/icons/icon7.gif

Thanks,

Jim

 

[nitwhit]

Re: Alternator Problem

I would highly suspect a weak/bad alternator or a faulty ground but I lean more towards the alternator since the problem occurs while it is functioning. Most car radios are much more susceptible to voltage drops than other electric devices, such as your blowers, so they will exhibit voltage/current problems more readily. Definitely pull your alternator and have it tested (any parts store can do it) or try and check it yourself with a meter.

 

[Cuyose]

Re: Alternator Problem

While you are in there, it never hurts going through all your grounds, clean them up, re-tightening, then hit them with a corrosion inhibitor like T-9 BoeShield or something.

 

[Eric 3.7LX Alpha 1]

Re: Alternator Problem

If you do find out you need a new alternator make sure the replacement is a marine one. They have added spark arrestors built into the openings of the alternator to prevent any spark from leaving the alternator and possibly igniting any fuel vapors in the engine bay.

You can check here at Iboats for replacement:
http://www.iboats.com/Mercruiser-Al...6547006--**********.435633797--view_id.269735

I got mine from Dbelectrical.com good price and quick shipper.
http://www.dbelectrical.com/c-7743-mercruiser.aspx

 

[Rocky_Road]

Re: Alternator Problem

Also make sure that your alternator drive belt is properly tight...a loose belt will not keep up at idle.

Happy boating!

 

[6meter]

Re: Alternator Problem

Wow! The 12th response probably got the right answer. When I opened this thread up, my gut reaction was a loose belt. Hope we're correct... cheap fix!