-97 50 HP 4 Stroke EPLT running rough - desperately seeking help

mobjunky

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Joined
Jul 6, 2014
Messages
1
Hi,

I have a 50 hp 4-stroke Mercury EPLT that has been causing grief for a year now. It starts and idles fine when cold, but when I accelerate it'll only go to app. 4500 RPM and sounds like it's running on 3 cylinders. This will continue after the choke goes off, but after some 20 to 30 minutes (longer in cold weather) it will pick up speed and eventually I get full RPM around 5700. But - then it will not run on lower throttle settings, and sometimes dies completely on idle.

This is what I have done to try and fix it:
- Carbs cleaned, tuneded and balanced several times with chemical carb cleaner and ultrasound. A professional workshop has tried twice in addition to my efforts
- Overhauled all 4 carbs with new gaskets, floats, needle valves, etc.
- Compression is fine on all cylinders
- Trigger, primary and secondary meters good on ohm meter
- Replaced spark plugs with new
- workshop replaced both ignition coils
- replaced plug caps
- replaced cdi unit (although with used unit)

I am completely at loss and so, apparently are the guys at the workshop.

Do anyone have any idea what this might be?

Thx
 
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