Temperamental Starter

[KetchiMan]

2004 Trophy 5.0L Merc # OWO18920, Bravo 3 Outdrive

Starter works great sometimes, and takes 20 key-turns at others. You can hear the starter click with every key turn, and when it finally does decide to engage, it fires up instantly and without hesitation. Started doing this last July and It's been off-and-on since.

1) Starter is almost brand new (my old starter did the same thing last season, so I replaced it last July)
2) Ignition (key) switch was replaced last year, with no effect on the issue
3) Neutral safety switch was replaced last July, and the boat acts the same whether the Neutral Safety Switch is connected, disconnected, or closed circuited with a bent paperclip. (Yes, the boat started with the Neutral Safety Switch completely disconnected...)
4) Corroded Negative battery cables were replaced 2 months ago when I de-winterized.
5) Batteries (2) are new last year and have 13+ volts, plus the boat fires right up as soon as the starter decides to fire
6) Positive battery cable between the bus and the starter was replaced today for a clean connection at the starter (positive cables between the battery, battery switch, and bus have not been replaced, and are a serious pain in the arse to get at behind the breaker board)

So, what am I missing?

 

[Scott Danforth]

you have a corrosion issue. clean every battery connection to shiny metal. these connections need to be shiny enough your kids can eat off them. replace the remaining cables as they are probably bad too.

the "click" you describe is simply bad connection to the stater somewhere.

when you replaced the cables, did you clean the mounting surface on the block?

what about the pilot relay.

 

[kenny nunez]

The solenoid that Scott is referring to is the small one on top of the engine, also known as a “boost” solenoid. It looks like a miniature solenoid of a Ford style. They are usually the problem , The wire color to and from on the large terminals should be yellow/red . They are easy to replace. To check it have someone turn the key to start and probe it with a test light. If you replace it try to get the genuine Mercruiser one, the off shore versions sometimes do not work right out of the box.

 

[Bondo]

Ayuh,.... Sounds like corroded connections to me too,....

 

[KetchiMan]

Is this what you're talking about?

 

[KetchiMan]

https://www.youtube.com/watch?v=W0SZMESBlcE

This?

 

[Bondo]

Ayuh,.... That's the slave solenoid, that power's the starter's solenoid,....

Changin' it won't fix corroded cables though,.....
Both ends of both battery cables are the most likely suspects,.....

 

[kenny nunez]

JUst like Bondo said, corroded cables will also cause the same problem that is why you need to test the circuit with a test light. The picture is the solenoid in question. I am betting on the solenoid being the problem.
When I bought my Donzi that is one of the problems that it had. Just for kicks I was able to take the solenoid apart and actually repair it by cleaning the internal contacts and bending the tabs back.

 

[wellcraft-classic210]

Worn brushes in the starter motor have been known to cause intermittent contact issues and results similar to what you described -- But it could be caused by a number of things in the circuit.

 

[KetchiMan]

Yep, it was the solenoid. $20 and literally 5 minutes to replace it.
Thanks everyone for the input.