84 Merc 80 - on/off peak rpm

Steveadore

Recruit
Joined
Mar 3, 2002
Messages
1
I'm hoping to get some suggestions on this problem. This is my first 2 stroke outbard motor. At full throttle the engine will run at ~3500 rmp then jump to 5000 for a few minutes. After that it it either drops back to ~3500 or dies out. I've checked the tank filter screen, it appears to be clean. The gas is fresh the full line is new. IS this a cabureator problem? :confused:
 

12Footer

Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: 84 Merc 80 - on/off peak rpm

If compression is up to spec, the next thing to check would be the carb. If you suspect the fuel pump also, (and you should), manually pump the primer bulb to see if the RPM's increase (it's best to have a mate do this,or pilot the boat for you).<br />If the RPM's go up durring pumping, the fuel pump should be rebuilt.<br /><br />This could also be 1 cylinder dropping-out from a coil or ignition failure,so check plugs for condition and color.
 
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