2000 Merc 135 bogs under load randomly!!!!!

Joined
May 25, 2012
Messages
15
Hopefully someone can help me out... Have a 2000 Mercury 135 outboard on my flats boat that will randomly die and cut off when I go full throttle. Sometimes it will not do it at all but most of the time it does. Always fires right back up and idles fine. Could this be ethanol? TPS? Timing? Its not happening all the time so dont think it's timing. checked fuel pump diaphragm and even added a gas tank vent where there was not one. Any thoughts would be great!
 
Joined
May 25, 2012
Messages
15
Re: 2000 Merc 135 bogs under load randomly!!!!!

Bulb stays fairly firm. what about low speed jets clogged? if I ever get up to high speed the throttle response is fine..
 

Dave1027

Lieutenant Junior Grade
Joined
May 25, 2010
Messages
1,078
Re: 2000 Merc 135 bogs under load randomly!!!!!

Bulb stays fairly firm. what about low speed jets clogged? if I ever get up to high speed the throttle response is fine..
That's possible. Have you tried opening up the idle mixture screws a half turn on each carb?

The reason I advised squeezing the primer bulb is to rule not enough fuel pump pressure at idle for any number of reasons like say weak diaphrams or air leak on the pulse port.
 
Joined
May 25, 2012
Messages
15
Re: 2000 Merc 135 bogs under load randomly!!!!!

No problem with idle. have not messed with any adjustment screws. which ones are they? there are 2 similar screws on each side of the 3 carbs. 2000 merc 135. doesn't appear to be optimax . thanks!
 
Joined
May 25, 2012
Messages
15
Re: 2000 Merc 135 bogs under load randomly!!!!!

its almost like the engine goes to a limp mode... checked both thermostats and they were filthy with scale and corrosion. Boiled them and they open late. maybe engine was getting hot and going to limp mode? what do you think?
 
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