trouble turning engine over

[jmillerfla]

I have an I/O with two batteries. When battery switch is on #1 engine won't turn over, almost like a dead battery sound. When on #2 the same thing happens. When battery switch is put to all, the engine turns over like normal. Batteries are newer and fully charged. Changed battery switch and the same result. Need help to figure out where a problem may be. Any suggestions? Ignition switch, loose wire?

 

[jmillerfla]

Re: trouble turning engine over

Hopefully, it is only a small electrical problem

 

[Bondo]

Re: trouble turning engine over

Any suggestions? Ignition switch, loose wire?

Ayuh,... Probably loose or corroded wiring connections...

 

[wire2]

Re: trouble turning engine over

What is the voltage between engine ground and starter lead when cranking on 1 battery? Now check the battery voltage at the posts, also when cranking. Big difference? Now work along connections with the meter to find where the drop is.
Even try a reading between the + post and the + cable clamp.

 

[Silvertip]

Re: trouble turning engine over

Your "newer" batteries may show via a voltmeter that they are fully charged but you are advised to have them load tested. Both batteries showing the same symptom alone but normal when paired suggests both are weak.