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Running in the drive way with the ear muffs on, I set throttle to 4000 RPM. Runs at 4000 RPM for about 45 secs then drops down to about 3300 RPM. Runs there for about 1.5 mins then gradually increases RPMs back up to a little over 4000 RPM....Any Ideas?
it is not a good idea to run a outboard motor that high of rpms on ear muffs its a real good way to blow it up !!! ear muffs are design for flushing a outboard motor out running at an idle speed after being in salt water, and to check and see if the water pump and impeller is working correctly !!!Quote:
Originally Posted by BobberStopper
:hesaid Good chance to run away if your not careful.
Do you have any problems while on the water?
I wouldn't run at that rpm on a hose. Water pump demand is higher than what the hose will supply. The 45 sec and 1.5 min times are consistent with thermostat times of opening and closing. I suspect it's a cooling issue. Re-test with motor in water. If the same occurs, shut down and pull spark plugs. Examine plugs and cylinders for the presence of water. You may have a leaking head gasket.
As a follow up, it could also be that the lack of water flow of the hose could lead to an overheat condition which will bring your electronics into a default limp mode setting. (you can research OMC S.L.O.W. for more details about the limp mode) If it doesn't do it on the lake, I would say you were over heating the motor on the hose at that rpm. 4000 rpm in neutral is too much. There is no 'load' on the moving parts and can lead to chattering of roller bearings. I'd try to keep it under 2000 in neutral.