Start problems 150 hp 4 stroke 2005

[ThomasvanBrenk]

Hi everybody!
I’m new on this forum and I hope that someone can help me.
I have got a Yamaha 150 hp 4 stroke outboard motor form 2005.
And have a start problem. When the battery is completely charged the motor will start directly. But when I like to start a second time the starter will come up but can’t go round. It looks like that the battery is empty, but it isn’t. I have got a new battery ( 3 new ones) and a new start engine but that does not help. It looks like that the engine turns around to heavy, because when I get some start help from another boat whit running motor It starts every time.

I think it’s a real strange problem and I hope someone can help me whit this.

Thank you in advance.

Thomas
The Netherlands

[WarEagle]

cranking amps

It sounds to me that you dont have enough cranking amps/capacity in the battery. And when connected to another battery the engine turns over just fine. Is this a recent problem? like it started fine with the old battery for "ever" until now. Are you sure the new batterys came with the same CCA rating?

[ThomasvanBrenk]

Thank you for your replay.
This is a new problem, I have the engine for 4 years and this is the first problem. I have replaced the battery for exactly the same one, for 2 times, because I was afraid the new battery wasn’t good. So it’s not a battery ore a start engine problem. But what could it be?
Thanks!

[WarEagle]

let me clarify

But it turns over and STARTS fine when ANOTHER battery is jumpered to it??? Where are you attaching the jumper cables? Jumper battery positive to where? Jumper battery negative to where?