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30 Liter running rough

newman

Member
"3.0 liter merc cruiser with m

"3.0 liter merc cruiser with merc carb. Carborator just rebuilt running great at idle and wide open throttle, runs extremely rough at no wake speed. Any ideas?
Could a sticky accelerator pump cause this problem?
Thanks"
 
What type of ignition ( po

What type of ignition ( points or breakerless )?
Have you changed out anything in the ignition lately?
 
Did it the problem stsrt right

Did it the problem stsrt right after changing them?
 
the problem started before the

the problem started before the tune up. the boat runs great except for that one spot at no wake speed
 
"New cap, rotor, spark plug wi

"New cap, rotor, spark plug wires and spark plugs?"
 
"How old are the spark plugs a

"How old are the spark plugs and wires? Use good wires, not a set that you make up yourself. Also, use the plugs listed on the plastic flame arrestor cover."
 
"Whenever you change plugs use

"Whenever you change plugs use anti-sieze on the threads of the plugs when installing. Spark plug wires is an area that I like to use high performance quality ( Accel, MSD, ect. ). It's worth going top quality on the wires, especially on a boat engine."
 
"No. Give me an update on the

"No. Give me an update on the plugs and wires, please."
 
Runs OK idling out of gear but

Runs OK idling out of gear but poorly as soon as you put it into gear at lowest speed?
 
"Was the carbuerator rebuilt s

"Was the carbuerator rebuilt seperate or at the same time as replacement of the plugs and plug wires, or was it before or after? Who did the rebuild of the carbuerator?"
 
If you are going to put new pl

If you are going to put new plug wires on then see what that does. Symtoms sound a lot like a defective plug wire. Most of the time when a wire goes bad it's after they have been moved. The terminal comes loose from the cable either because of a poor crimp when being made or being pulled hard or both. Once arcing occures at a loose connection it gets worse.
 
Go into the distributor. Grab

Go into the distributor. Grab the rotor and check for how much play/wobble there is with the shaft.
 
"turns out that part of the ve

"turns out that part of the venturi assembly was clogged ,reamed it with some heavy mono filament boat runs great thanks"
 
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