Mercury Thunderbolt 500 (50 HP) wont start

Hi,
I jus bought a two stroke Mercury Thunderbolt 500 (50 HP) outboard for my boat. The engine was winterized when I purchased it. After charging the battery, adding fuel mix and lower unit gear oil I started the engine (at home with running water) and everything was fine. I engaged the propeller in both directions and it all functioned well.

The next day I took the boat to the marina and the engine won?t start. After I switch the motor, the starter engage the flywheel and turn it for a short distance and stop (i.e. the starter will not keep running the flywheel) and some times it will not turn at all. I thought maybe the battery was not good so I connected it to my car through jumper cable. Same results.

Do you have any idea what is going on?

Thanks

Re: Mercury Thunderbolt 500 (50 HP) wont start

I would recharge your battery. I have a thunderbolt 500 as well and I tried to do the exact same thing you did with my truck battery. Your car battery does not have the power to turn over this motor. Charge up your boat battery and I think it will fire up, mine did. Good luck

Re: Mercury Thunderbolt 500 (50 HP) wont start

grew153owner said:

Your car battery does not have the power to turn over this motor.

Click to expand...

What? That's just not true. A car battery is more than sufficient to crank over that little 4 cyl Merc. The fact that boosting the motor had no affect points to another problem.

You more than likely have a poor connection in the starting circuit. Remove and clean all connections then re-install and tighten each connection. Failing that, your starter motor may be defective.

Re: Mercury Thunderbolt 500 (50 HP) wont start

My dad and I thought the ignition switch was bad. So we troubled shot the starter without the switch (by passed it) and the problem persisted.

We then decided to take the starter out to a friend of ours who specializes in motor winding. It turned out that the Armature winding is defective in one area thus starter sometime works and sometime it does not.

I guess we need to get new starter.

I am trying to get my engine model number, but I had not been successful.