Mercury 500 1971 50hp won't start

[alexegg]

Hi everyone,

I recently started restoring an old Mercury 2 stroke, from the decal and internet, I believe it's 1971.
I manage to start it few times and run it for few minutes outside the water, but when we tried it on the water, it wouldn't start anymore.

I'm an okay mechanic I think, I've checked that I have sparks, and compression, and fuel.
This boat has been sitting for a LONG time I believe. But now it won't start anymore and even tho the batterie is perfectly charged (I've even tried while connected to my truck running), it acts a little weird in terms of resistance when I try to start it. Same when I tried starting it manually, sometimes the engine would be kinda "locked" really hard and completely prevent you from pulling the cord.

I've uploaded a video here to show you. What do you think ? (for the purpose of this video the water was off but it was on when we ran it obviously)

I think I have the starting sequence ok as well (small lever to the end, neutral, pump the bulge few times until hard, choke on)

On a side note, it looks like gas is leaking from the carb (it's a dual carb). I've started taking the whole carb away to clean it meanwhile, thinking maybe that's the problem, but it would be weird it was running before and now the 2 carbs would be both stuck/dirty.

Thanks a lot for your help !

View attachment Merc_start.mov

 

[racerone]

Checked the gear oil ?---Install a new impeller.----Check fuel pump diaphragms.---Load test your battery even if new.-----Take starter apart for inspection / cleaning.----Inspect battery cables.-----Check belt timing.

 

[alexegg]

I've checked all of these yep. New gear oil, fuel pump works fine, tried 3 batteries. Starter works perfectly and it does the same thing when I try to start it with a cord, gets some really strong resistance at some specific points just like you can see on the video when the starter even gets stopped because the engine offer loads of resistance

 

[racerone]

I say there is something wrong with your motor, yet you say that the starter works " perfectly "-----Maybe pull the motor apart to check the bearings.

 

[alexegg]

The bearing of the starter ? I've opened the starter already, I've rebuilt many of these, it's totally fine. There's something wrong with my motor indeed, that's why I'm posting here to try to get advices on what could it be. The engine ran a week ago, and there weren't any of these resistance shocks that you can see on the video

 

[racerone]

Trouble shooting on YOUR motor needs to be done.----Good luck with it.----Bring it over as it won't take long to figure out what is wrong..