Re: Starting problem
Turn on a light your can see like your anchor light and try to start while watching the light. Does the light go out??
Yes both batteries can go bad at the same time. How are your batteries wired?? Thru a battery switch?? If thru a switch in what position do you leave the switch in?? 1?, 2?, Both? off?
Can you turn motor over by Hand with a wrench on the front? Have you tried removing your spark plugs and trying to turn over?
If when you try to chank the motor the anchor light goes out or gets very dim then the battery voltage under load does not have enough current to trun the motor over. This can be a bad battery, A bad cable or connection, or a engine cylinder full of water. If the light stays on and is on the starting battery and the motor does not turn over then likely a bad starter solenoid.
If you leave the battery switch in both then you may have a bad cell in one battery that will discharge both batteries.
You can check your batteries while cranking with a voltmeter and see how much the voltage drops. Should be 10 or so. Having batteries load tested will check the batteries as well.