Mercury Outboard 500 50 HP

[xangmoua]

I recently bought a Mercury 500 50hp and everytime I put it into gear it will bog down right away. I'm pretty much stuck and have no idea why its doing this. It shifts into gear and accelerates perfectly outside of the water but once you put some water pressure on the prop it boggs down. I've done a compression test on all 4 and it is a consistent 125 on all. If anyone can help point me to the right direction i would appreciate it. This is my first boat and im not an expert on this so any help would be greatly appreciated. Here is a short video of what it looks like right now.

https://www.youtube.com/watch?v=VVn2xhqp728

 

[jimmbo]

It might not be firing on all four cylinders. The carbs may be set too lean, or may be dirty, the sync between the carbs and spark may be out of spec. One carb might not even be supplying gas.
So you have some basic troubleshooting to do. Does the spark jump a 7/16" gap. Initial idle mixture screw is about 1 1/2 turns out from GENTLY seated. Final Adjustment needs to be done under load, in gear.
Idle speed in gear, should be about 600 - 650 rpm, roughly 800 in neutral

 

[racerone]

Open low speed mixture screws 1/4 turn at a time and test run.