1975 Evinrude 9.9 Loses power

[Married_but_not_dead]

Hi everyone i have a1975 omc 9.9 on a 12 ft alum runs great EXCEPT when on the water and want to go to the other end of the lake will power up and be going good at wot all of a sudden will slow down at wot to almost idle speed back off on throttle and engine quits.Restart and won't even rev in neutral. Change plugs on the water away you go again till it happens again could be 5 min could be half hour could be ?????? no telling. Any help to make fishing fun again would be appreciated. I live up north so don't get out much right know looking for input/help. Complete tune up done and carb o/hauled seems to be better with hotter running plug.

 

[OptsyEagle]

Re: 1975 Evinrude 9.9 Loses power

Sounds like you are fouling out your spark plugs. When the first one goes, you lose a ton of power and of course when the 2nd one goes, you lose everything else.

What plugs are you using?

 

[Married_but_not_dead]

Re: 1975 Evinrude 9.9 Loses power

Sounds like you are fouling out your spark plugs. When the first one goes, you lose a ton of power and of course when the 2nd one goes, you lose everything else.

What plugs are you using?

Started with NGK BR6HS then lost the resistor and went with B6HS seems better but still acts up Plugs are clean when i remove them.

 

[sutor623]

Re: 1975 Evinrude 9.9 Loses power

What is your oil mixture? Have you tried leaning out the motor a bit and seeing if your needles are off? I have seen 15hp and 9.9hp parts interchanged, like exhaust housing, reedvalves/reedvalve spacers, carbs and all that mess. The 9.9 with the 15hp carb (and 9.9exhaust and reedvalves)will foul up plugs at trolling speeds, cause I have done it.