Mercruiser 4.3V with No Power

[cringe]

I have a 2002 Bayliner Capri with the Mercruiser 4.3V and Alpha 1 (and Thunderbolt IV ignition if that matters). Started it the other day and it ran for a minute then it unexpectedly shut off. Now there's no power to anything except for the trim (and trailer) button. I turn the key and nothing happens, no noise, no clicks. The tilt switches are dead (blower, lights, bilge, etc). From what I've read, I should suspect the 90A fuse on the starter but it "seems" to be ok but I don't know. I checked a few things.

Marine battery is only 4 months old, has 12.7v, I had it tested at AutoZone, they said it's still good.
90A fuse on starter has 12.7v on bolt, orange wire into alternator has 12.7v too. (See pics).
50A circuit breaker has 12.7v on one side and 8.9v on the other side. That 8.9v seems odd to me. Breaker does not seem to be popped out. I pushed hard.

Could there be any inline fuses I need to check? I have not inspected the cannon plug yet. Thanks.

Chris

 

[Bt Doctur]

you need to clean the corrosion off ALL the connections beginning at the starter
The manual says"Clean and Tight" not "Green and Tight"

 

[achris]

...50A circuit breaker has 12.7v on one side and 8.9v on the other side. ...

And that's with no load. As soon as you load it up, that's going to drop to near nothing. Either a loose/dirty/corroded terminal, or a faulty breaker.

Chris.......

 

[cringe]

Makes sense. I will clean the connections and report back after that. This boating stuff is still new to me, learning as I go.
Another question, do the tilt switches get power through the 50A breaker too?

Thanks!

 

[Bt Doctur]

no, power for the trim is a #10 or #6 Red and Black to the battery, power for the solenoids is a 20A fuse coming off the main buss bar

 

[cringe]

Maybe I used the wrong term. By tilt switches, I mean blower, nav lights, bilge pump, etc, to left and right of steering wheel, not the trim on the remote control. I figured the trim was on it's own circuit since that's the only thing that has power. Thanks.

 

[Bt Doctur]

Trim and Tilt are together
everything else gets power from the 50A CB , it gets power from the main post on the starter.
Start at the starter, get everything nice and clean, then do the same at the 50A CB posts and it should clear everything up

 

[achris]

Maybe I used the wrong term. By tilt switches, I mean blower, nav lights, bilge pump, etc, to left and right of steering wheel, not the trim on the remote control. I figured the trim was on it's own circuit since that's the only thing that has power. Thanks.

Rocker switches is the correct term. And whether they are powered through the engine harness is something only you can determine, by checking where the rocker switch panel gets it's power. My personal preference, and how I wire ALL boats is to have engine and 'non-engine' electrical systems isolated. Last thing you need is for a non-engine item to be shutting down you engine electrical system, or for your engine systems to go out and take down your radios (and your only means of contacting help)....

If the engine 50A breaker pops and everything on the rocker switch panel dies, then I would be changing that quick smart! Run a seperate red/black pair, about 6mm with its own 50A fuse/breaker, from the battery isolation switch up to the dash and install a couple of terminal blocks. One with a red cover and one with a black cover. I think you can guess the rest. Heres' one I did a while ago. And I also remove all the 3AG glass fuses. I put mini blade fuses in, with water resistant holders and covers. I mention them quite a lot, have a search around on threads where people complain of intermittent complete power loss, or 'no start'.....




Chris.........

 

[d3nnisc]

No Title

Had the exact same thing, boat would start and than die after a little while.
I could also shut down the engine with every rocker switch on the dash.
Turned out to be the plug under the dash that connected the main wire harness from the engine to the front and from there to all the switches, completely corroded.
might wort checking out.
have to agree with Chris, running separate wires is the best way...

 

[Gsex10]

Just had this same issue with my 2007 Crownline and got some good tips on things to check in this Forum as well as I found two Youtube Videos posted by people who also had this exact same issue. 50 Amp Circuit breaker engaged, No Power at Key switch and no radio, Yet Navigation Lights,Bilge, and Blower all had power and worked.

In one video The problem was the 90 amp fuse down on the Starter and in the other video the guy changed the 90 amp but it wasn't the problem. His issue was a 15 amp mini fuse at top rear of motor behind the distributer. You can test the 90 amp by ensuring you have 12 v to the orange wire at the alternator If no power you need to replace the 90 amp Fuse. In my case the 90 amp fuse was fine but that 15 amp mini fuse I describe was the culprit . New 15 amp fuse and boat started right up.

Hope this helps.

 

[cringe]

Put a jumper on the 50amp circuit breaker to bypass it and the engine cranks, starts and the rocker switches work. FYI.

Gsex10, I looked for the 15 amp mini fuse for future reference, could not find it. What does it protect? What color wire? Thanks.

 

[Desertson1410]

Just had the same issue it was my 50 amp fuse