97 40 merc can't figure this one out

[bb572ci]

I have a 40 merc 4 cyl that is running poorly on aceleration and top end. I did the normal checks and then sum. 135 compression on all 4 clean blue spark on spark tester 1/2 gap replaced entire fule system tank hoses ball rebuilt the carbs set the float level all new hoses on the motor reseculation and all fule pump rebuild. The oil injection has been removed including the tank. pre mix now. The boat will get on plane but only with the cowling off and even the at wot it sounds rich and if I lift of the throttle to 3/4 or so it cleans up and sound good but still not 100%. The spark plugs look to clean to me for a 2 stroke. I have been working on 2 and 4 strokes for 18 years this ones got me stumped. dynamite is the next tool That comes to mind. please help if u can. Thanks

 

[enginepower]

If plugs don't have at least some light brown to them, you are running lean. Try pumping the bulb when trying to run it and see if it goes ok. If so, your fuel pump has a torn diaphragm.

 

[enginepower]

If plugs don't have at least some light brown to them, you are running lean. Try pumping the bulb when trying to run it and see if it goes ok. If so, your fuel pump has a torn diaphragm.

 

[bb572ci]

It has surface gap plugs they do have spark trail but no color except were the spark is traveling I also tried to pump the ball while running with no differance then I tried to choke it while pumping the ball same thing

 

[enginepower]

Ok so if all cylinders have spark and good compression, you are looking at a timing issue or lean carb. I would say you probably have some blockage in your jets if plugs have no tan/brown color. Only other thing I can think of would be a reed issue maybe?

 

[bb572ci]

I will recheck the timing. I already checked the reeds I thought the same thing. Did the carbs when the issue started. I did a check with a dva meter on the stator the low speed winding is good at cranking speed and running but the high speed is off at cranking speed but good at test rpm 4000. Thanks