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High Idle, Cannot retard /change timing to change RPM

C

Canufixit

Contributing Member
I've spent some time searching for this issue on line with no findings ....

Background ... 1997 Merc 2 cycle 60hp was running great for the past 2 years - left in water/did nto start for 1 week. On next usage Starts hard, Idle too high (1800 - 2000 RPM) runs rough.

Suspected Water in the 1/4 tank of Gas - used water detector past - no water. Added Dry gas and 10 gallons fresh Gas Just in case, no change.

Thought it might be Vacuum leak - found none visual and soaked the carbs outsides, gaskets and hoses with starting fluid - no change in RPM/roughness - so vacuum leak is not suspected. Throttle plates in carbs (3) all fully closed and still runs high RPMS.

Checked Plugs and spark - Plugs look ok but a little wet - changed them.

Spark is apparent to all cylinders.

Checked Compression - all the same (3 cylinders).


I'm Focusing on high idle. I marked, then moved the trigger plate about 20 deg - with no change in RPM.

I "Think" the timing is not changing. It does not appear that rotation of the trigger plate does not change RPM. So ... I expect it to be the Trigger plate or the Switch box. Since the Trigger plate is just a set up pick up coils (In my opinion?) and the switch boxes are known to fail I've ordered a new switch box.

I'm thinking that the trigger must be working or it would not even know when to fire close enough to start. Tuesday I'll get the switchbox and swap it out.

Any Suggestions?? If it still fails I'm leaning towards pulling the flywheel and changing the trigger.

Any help/comments/suggestions appreciated.
 
SOLVED/ FIXED ! Ii was the Stator or the Trigger.

Although I did Ohm test the Trigger Early on, (which tested OK) I finally decided to pull the Flywheel. I changed the Both the Trigger and the Stator.. The top crank seal looked fine and no sign of fuel/air/exhaust leakage - but while I was there I changed it as well. Reset idle timing. Did some final link and sync/idle/low speed jet tweaking - runs like new! I will re ohm check the Stator and Trigger on the bench and IF I fined any bad readings to indicate which item actually was bad - I'll add another post.

Quick history summary for anyone searching for this issue;

Mercury 1996 60 HP ELPTO Engine. Was running just fine/OK . Left to sit in water for almost a week. Cranking was harder and labored. Did start and idle but missing and very rough. Could NOT adjust idle to go under 1500 RPMs. Ran overall VERY rough at any speed.. Would not exceed 4K RPM. Throttle response was much different that normal - (not very responsive to throttle changes) .

Issue found - Although trigger ohmed out OK it was changed (with a new OEM) along with a new Stator (CDI). Not sure which was the problem . Issue fixed.

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