1988 60 HP Evinrude ?pulsating? at above ? throttle

[MiloKnezevic]

I have issues with 1988 60 HP Evinrude ?pulsating? at above ? throttle.

I used 50:1 mix gas tank was topped of last week of June and I did add some stabilizer to it 1st week of July when I realized I needed different engine. I made sure there were no air bubbles in fuel line, yet I still had to spray a bit of ether to get it started.
All fuel connections seem to be tight and I do not think I can detect any fuel leaks. I believe that carburetors have been rebuilt, new plugs, pistons & rings have been also put in by the seller; this is the first time this engine has been in the water since I got it.

Engine starts just fine after it has been warmed up. It shifts easily both forward and into reverse.

Everything is fine as long as I do not go over 1/2 of the throttle.
After driving at various speeds (still in the process of breaking in rebuilt engine) I did get my 17 ft aluminum boat to plane at about 3/4 of the throttle. The issue I am trying to understand now is why does the engine start hesitating / pulsating after I go over 1/2 on the throttle. It is as if it looses power (does not shut of, just slows down) and then picks up again? at 2 second intervals, 2 seconds going strong, 2 seconds slows down...then back to strong, then back to slow down.

I do not have tachometer nor GPS, so I really cannot quantify at what point this exactly takes place, certainly seems that this behavior starts at above 1/2 of the throttle. I was on the water for about 1 hour and 15 minutes, just going through different throttle settings; this hesitating and pulsating was taking place throughout that time. The engine does not cut off or anything like this, it simply it seems like it is not getting enough gas.

I do not believe that the engine is overheating.

Can you please let me know what do you think I am looking at here?

Thanks,
Milo

 

[freddyray21]

Re: 1988 60 HP Evinrude ?pulsating? at above ? throttle

sounds like an air leak somewhere. Could be in the carb or lines. On of the shafts maybe. start it at an idle and spray some carb cleaner around the carb, but not into it. If it changes rpm up or down when you spray it the spot you are spraying is where the leak is. You should not have to spray ether to get it to start cold if the choke is working right. Makes me still think it is a carb or line leak. Have you replaced the fuel line from the tank to the motor recently. If not and it's been awhile you might think about it.