Engine dies at acceleration only.

[Country Dirt Kid]

Firstly, thanks for all the help so far. I have a 1981 20 hp Mercury that would not start at all. I disassembled the carb and cleaned with carb cleaner and a can of compressed air. Now the engine runs like a champ at idle and WOT. The problem now is that most of the time the engine bogs down and dies when I open the throttle to get on plane. I must have missed something. Why would the engine run great except at acceleration? Here is what my carb looks like

 

[jimmbo]

Well, as always, the 1st place to start is Compression Test.
When you said " I disassembled the carb and cleaned with carb cleaner and a can of compressed air.". When you "disassembled" the carb, did that include removing all the Welsh plugs? If not, some crud may still be blocking some of the off idle circuits of the carb, resulting in a lean condition during acceleration until there is enough air flowing through the carb for the Main Fuel Circuit.
Another issue that may or may not be the culprit. When you reinstalled the carb, did you verify the Sync between the Carb and the Timing Advance?

 

[Country Dirt Kid]

Another issue that may or may not be the culprit. When you reinstalled the carb, did you verify the Sync between the Carb and the Timing Advance?

Ok I will rent a compression tester today. I did not pop out and clean behind any of the welch plugs in the carb either. I can also rent a timing light. The engine manual gives instruction for adjusting the timing at wide open throttle in a test tank. There is no way I can do that in the tub of water that I use. I have heard that there is a trick to doing this by myself at home. Does anyone have any information on that.

In any case I plan to do the following
1 Test compression
2 verify good spark with a spark tester.
3 Clean behind welch plugs on carbs
4 Set timing
Does this look right?
Thanks

 

[jimmbo]

Max Timing is set at the factory and should be good for the life of the engine. It should not change,unless someone changed it. Pick Up Timing can end up a bit off a bit when the carb(s) are R&Red, but usually a verification is all that is needed. Those timing checks can be done at cranking speed(the max timing spec might be different at cranking speed due to the Characteristics of the Electronics).