So, troubleshooting my poor low speed performance of my j200TXEUA, I tested the external check valves according to the factory manual. Five out of six were not working. Upon removal, most of them were missing the screen and valve, making them a straight fitting. I thought it would be best to remove the manifolds and check the internal valves. Suprise! There weren't any! I'm hoping this wasn't some service bulletin modification, and ordered them up today. So out of twelve, I had one working valve in place, and that one was missing the screen. Too bad they cost as much as they do, but that's boating. Sure hope my engine is better after this. Also doing carbs with new floats, etc.
make sure the hoses and engine fittings are clear also. A small syringe such as available from a hobby shop and a short length of model airplane motor fuel hose works great. Fill with ordinary isopropyl alchohol and shoot through the fittings and hoses to make sure they will flow.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.