90 HP Inline 6 No Power

[NWMI]

This winter I bought a fishing boat with a 1986 90 HP Merc inline 6. I went through the carbs because it would idle OK but no power when I open the throttle. I checked compression with good results, 115-120 on all 6. Really strange, it sounds too quiet with the throttle open and runs very smooth but there is no power, won't get the boat on plane. I had it out for a few hours of messing around and once it took off like crazy for about 2 seconds then back to no power again and I couldn't recreate that. I bought a manual and plan to sync the system but I don't think that should affect output this much. Any ideas?

 

[Texasmark]

My guess is ignition, like you are only running on 3 then the other 3 kick in. Corroded electrical connection associated with the triggers.....signal, power, ground.

 

[emckelvy]

Or a bad hi-speed stator winding, a very common problem. You can check resistance of the high and low-speed windings with a meter. Or, pick up an inexpensive "DVA adapter" and do active-testing, the voltage readings will tell you a lot.

Link to cheap Digital Voltage Adapter: http://www.americastoolwarehouse.com/automotive-tools/ESI-640.html

LInk to CDI Electronics troubleshooting information for outboard ignition systems:

http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true

Start at Page 70 for Mercury ADI (Alternator Driven Ignition)

HTH...........ed

 

[Chris1956]

Does she die when you give it throttle, or is there no change? If she dies, the idle mixtures on the carbs could be set too lean.

 

[NWMI]

I will check the stator windings. Thanks for the replies. It doesn't die, the first quarter throttle feels a little week then then I can go from there to full with no change in power but the motor actually sounds quieter.

 

[NWMI]

New stator and it runs great. Thanks all for the help.