rpm under load problem

[mccrea]

my port 135 mercury 1992 carburated outboard is giving me grief and would like some help. at 2200 rpm under load and advancing throttle to full the rpm stays at 2200 and does not increase rpm. carburaters are clean and fuel is clean. engine starts right up and idles at 900 rpm and in gear about 800. all linkages are set correctly<br />and i get 130 lbs of compression in each cylinder. does anyone know the 92 engine and help me figure it out. i had the boat out today and engine runs fine until 2200 rpm.<br />thanks for any help / also plugs are firing with a brown tip<br />thanks

 

[Coolmaker]

Re: rpm under load problem

Sounds like the linkage is sticking and preventing it from going to WOT..

 

[mccrea]

Re: rpm under load problem

linkage is smooth in neutral and load / i can watch it advance fwd but no rpm advance. thanks<br />mike

 

[achris]

Re: rpm under load problem

Throw a timing light on it and watch the timing advance. Don't take it that just because the linkages move, then the timing is advancing.<br /><br />Chris.........

 

[mccrea]

Re: rpm under load problem

thanks chris ill do that im a little perplexed as three days ago it was fine with same settings<br />mike

 

[tengals123]

Re: rpm under load problem

not that it will help, but had the same issue with my old 68 merc 1000. started idled perfectly up to 2400rpm under load. The last 40% of carbs did not do anything. Found out it was only firing on 5 not 6 cyls. Make sure you have great spark at WOT on all cyls.<br /><br />cheers

 

[mccrea]

Re: rpm under load problem

just returned from checking advance with a timing light and spark advances as the book notes.<br />thanks chris