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1976 15hp Evinrude running low rpms

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warrendorsa

New member
The rpms on my 15 hp 1976 Evinrude outboard suddenly slowed down and I can not get it to run the rpms it was before. Any ideas on what needs to be worked on? I rebuilt the carburetor about 2 years ago.
 
Correct.-----But post the results of a compression test here.-----Those YouTube videos can be a huge help.----But some are for entertainment only.-----Check fuel pump diaphragm.----Check for water in the fuel.-----Mixing at 50:1 gas/ oil ?-----Water pump impeller needs to be replaced about every 5 years.
 
Sorry---I guess I missed the " new fuel pump " in post #1.----What else can you tell me about this motor.?------I have all the parts and know these motors very well.
 
About 2-3 years ago I rebuilt carburetor, put new fuel pump on it, put new water pump in it, and replace plugs at beginning of each spring. It was running great and one time near end of last summer we were cruising across the water when it suddenly dropped rpm’s. It has been running lower rpm’s or getting up to good rpm’s then immediately drops off since then. I did notice recently idle speed adjustment knob had broken off so I just replaced it. It was my dad’s motor so it is a very special motor to my son and I. Any help would be very appreciated.
 
Start motor in your test bucket.-----Remove top plug wire.----Note what happens.-----Install top wire and repeat test.----Pull off the bottom wire note the results.----I suspect it is running on 1 cylinder.
 
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