Yamaha 4 Stroke starting problems

[markoantoniovt]

Hi: I have a Yamaha F25 D 4 stroke and Yamaha 704 Remote control box on my pontoon boat. I am guessing the motor is about 12 years old. Back in 2015 I got injured and did not use the boat for 2 years. It sat outside but was well covered. When I started using it again, it developed a starting problem. It turns over slow sometimes. When this happens you can turn the key off and most of the time (but not always) try it again and it will start just fine. If I leave a 2 amp charger on it for a couple of hour and try to start it, it turns over just fine. But shortly the problem returns where it turns over hard. I have replaced the battery. I have checked and cleaned the battery connection. When I put a voltage meter across the battery and it starts fine, the voltage does not drop a lot during the starting process. When it starts hard, the voltage drops significantly during the starting process. I can not see where any of the electrical lines are corroded or or have been chewed. Maybe the starter needs to be rebuilt? I am at a loss and any help or pointers would be greatly appreciated.

 

[JeffJay]

You may have already done this when replacing the battery, but I always start by checking for corroded/lose ground wire connections. Take an ohm meter and ensure you have ~0 ohms between various ground points on the electrical system (e.g. starter ground and battery ground). A work-around might be to install an on/off switch on your battery to prevent current leakage during storage (it would also help you determine if leakage is part of the problem). Intermittent wiring/electrical issues are a real pain.