1969 Merc 1000 starts, idles, runs but wont rev

[FZ1]

Hi. I'm in dire need of a quick suggestion on where to look. 1969 Merc 1000 that has had carbs properly cleaned and link n sync and good fuel and new plugs etc. Its not a simple thing. It will start and idle on all 6,.... run on muffs perfect (of course) then under load will not rev past 2000rpm or so. Almost as if it had a low speed and high speed coil. But it doesn't. Does it? Its running on all 6, the carbs are opening fine, and the advance is dead on acording to the manual. Theres no stumbling or stalling,... just wont rev. HELP?!!!

 

[emckelvy]

Re: 1969 Merc 1000 starts, idles, runs but wont rev

How big is the boat and what style hull? What pitch the prop? Makes a big diff, if the motor's overloaded from a prop with too much pitch, it won't rev up.

Or could be a freak thing like some sort of restriction (carbon buildup, broken parts??) in the exhaust tuner or in the lower unit. You could pull the lower unit and inspect with a strong light to rule this out.

Other things that might make it run poorly are main jets improperly-sized (too big or too small); leaking fuel pump (but likely it wouldn't idle as well as it does).

Assuming of course the engine's innards are healthy. Compression check sat??

Hopefully some of the Guru's will chime in with more suggestions.

HTH & let us know if you find the problem........ed