99 mercury 200 hp carb: Cylinders 1 and 2 wont fire.

[countryguy12]

So i have a 1999 Mercury 200 xl Carb Serial number og805600! Iv been trying to diagnose a rough idle problem for 2 weeks now! So far i know that cylinders 1-2 are not firing but are getting spark and fuel! Engine has no problem starting and doesnt stall at all! Just runs rough and idle seems to be high! I can pull the spark plug wires off both cylinders with no change in how it runs what so ever and also i can screw in the mixture screws on the carb all the way with no stalling. So far Iv changed trigger, stator, both rectifiers, reed valves, cleaned and rebuilt all the carbs, fresh plugs, and timed everything. Compression in all cylinders is 120 and fuel pressure is at 5 psi. Iv done dva tests according to the mercury service and everything checks out. I cant figure this out for the life of me. Talked to 2 marine mechanics which both tell me this things should be running like new. Can anyone help me out here please?

 

[jimmbo]

Is fuel actually getting to those 2 cylinders? Have you tried spraying some gas-oil mix into the carbs to see if it makes any difference? You removed/replaced a few parts, all gaskets sealed? All wires between the switch boxes and coils wired correctly, so each cylinder is firing in the proper order?

 

[dreamcruise]

Is there Spark? Did you check compression?

 

[Dukedog]

1 and 2 have only one "common part"... top carburetor,,,

 

[Faztbullet]

Take a squirt bottle filled with 50:1 mix and squirt into throat when running. If it picks up go back thru carb....