Reply To: 7.5hp Evinrude won’t idle

[Don]

Tell us a little more.  When was the last time the engine idled normally?  What work was done to it between then and now?  Like everyone says, stick with simple things.  Check compression, look at the plugs for signs of water, etc .  Does it seem like the engine is dropping a cylinder when you slow it down?  Or, does it just run normally but cut off whne the throttle is lowered?  Are you sure the carb sync linkage is OK?  Perhaps the carb butterfly/throttle linkage is stuck open slightly for some reason.  Keep in mind that the choke linkage opens the throttle slightly when the chokes is activated.  So, of the choke linkage is messed up, the carb butterfly will be held open slightly at low speeds which will cause it to stall out.  Is the carb synced properly to the ignition cam?  Have you messed with that adjustment at all?  If you tried to adjust it while the choke was out, then it will be way out of whack and might be holding the butterfly open.

You might want to invest in those cheap neon inline spark testers.  Remove the cover, install the testers inline to the plugs, then run the engine.  Perhaps you are losing spark to one cylinder at lower speeds.

Finally, and perhaps I should have led with this….  Those throttle indicators on the twist grip are notoriously inaccurate.  Does the engine seem to idle properly while it is at the start position?  Are you judging idle quality based soley on that twist grip indicator?  If so, perhaps there is nothing wrong with the engine at all.  Has someone been messing with the throttle/twist grip/horiztonal/vertical throttle shafts?  If so, perhaps the gears are not lined up properly.  Again, these twist grip throttle indicators are notoriously inaccurate, so please don’t judge idle quality based soley on the twist grip throttle position indicator.