Intermittent starting

[concordia]

I have a 1993 Formula 31PC with twin 454's mercruisers. My issue happens on either or both engine when I try to start them. Very random. Sometimes no problem at all. Both batteries are fully charged and connections are good. Does this boat have only one slave solenoid? Is it located on the starboard side of the engine compartment, forward of the batteries. Thanks for any help.

 

[Jeff J]

Does it crank, not crank, click, solenoid rattle…? Guessing from your post that it isn’t getting consistent power to the starters but it’s just a guess. If that is correct, has there been any troubleshooting with a multimeter when it is acting up? Does it seem to happen more when the ambient or component temperatures are hot or cold? Random seeming issues are usually a bad connection. Most commonly in my experience is soldered joints but could be also be a broken wire or connector making an intermittent connection.

 

[Scott Danforth]

each engine will have a slave solenoid. however on your 34 year old boat, start by cleaning every connection from the battery to the motor to the helm and back. that is both power and grounds.

by clean, I mean shiny sparkly clean with 150 grit. clean enough your grandmother would eat off it clean

 

[DeepCMark58A]

If you have a bilge you have to be mindful of connections.

 

[airshot]

Full charge on each battery means 12.6v minimum ! Have you done a load test? Batteries can show full charge with no load, then fail when a load is put on them. Load test needed for sure.

 

[Jeff J]

Battery is not a bad guess but I have never seen an intermittent battery. It will be a connection issue of some sort and it will be something both motors have in common unless there are 2 identical problems on both motors.

I once owned a 1974 Cherokee. It was having some intermittent starting issues. I grabbed the parts shotgun and wasted money. It finally got fixed when I went to start it and the positive battery cable nearly melted at mid span. It had a corroded area that was easily seen after the insulation burned off.

 

[alldodge]

Not necessarily yours but many boats use a single Bat to start both motors and can have 1 or 2 other Bats for the house loads. How is yours configured?