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Only getting 1/2 throttle

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oldevinrude

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So I was out this morning, I've got e25rend, 1992 25 hp 2 stroke evinrude. It starts no problem idles smooth but I'm only getting 1/2 power, only 10 of the 20mph it normally goes. Still running smooth...I blew out the carb, everything is clear. Fuel pump is OEM and has less than 20 hours on it. Any suggestions? Thanks in advance.
 
Sounds like it is running on one cylinder.----Some trouble shooting to do.-----Could be a bad sparkplug.-----Do a compression test , post your numbers.-----Check for spark on both leads.-----Could be a broken reed valve.----Did the issue show up suddenly ?-----How did it run for you last week ?
 
Started out as intermittent...full speed then slow for a second... then just slow after about 15 minutes. Plugs are new, wires are new...new flywheel, new power pack
 
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Have to ask.----Why a new flywheel ?----So does spark jump a gap of 3/8" on both leads ?----Wait , bring it over it might be an easy fix.
 
the old flywheel was out of tolerance and kept shearing the woodruff keys...are you in St. Augustine, FL by chance? And boat is at the storage place for the night, damn HOA...
 
Just joking , I am too far away.-----The flywheel key locates the flywheel for proper timing.------Same key used on 9.9 and 250 HP motors.-----The flywheel is driven by the locking tapers if they are in good condition.----Some inspection as per previous posts must be done.
 
It's lined up right, fits good and tight. I think you're right about the one cylinder...I noticed that the exhaust sounded different when I was fishing the motor...a little more hollow sounding... gonna check the wire resistance and plugs and coils tomorrow
 
Revisit post #4. I like 7/16 to 1/2" sharp snappy spark jump. Could be a bad external coil, look at it in the dark, could be arcing to ground.....sometimes you can even hear it. Coil will still test okay with ohmmeter, but arc out at higher speeds...... exactly your symptoms. Occasionally they will arc internally, harder to detect....you can try switching the coils and see if the cooler running goes to the other cylinder.
 
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That's how I've been going at it, start at the easiest problem. Occam's razor. It'll run good for a month or so, then something else will go. But for a 30 year old motor, when she's running, she runs strong!
 
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