70 HP Evinrude sluggish when throttle up

[pnflaitz@infoblvd.net]

Every once in a while the engine will get very sluggish and won't even run enought to plane the boat. Give it a few minutes and it might take off again or it may be a long ride back to the cottage. A couple of times it has happened after the boat has been cruising at a decent speed for a while. It's almost like the engine just doesn't want to go anymore. It always idles fine and runs great at lower RPMs. Never had a problem with starting or stalling. Any ideas on what this might be. Not too technical, I'm new to all of this <br />Also, I changed the lower unit oil and didn't pay attention to which screw went on which spot. One has a longer tip on the end of it and the other one is a lot shorter, but both the same diameter. Any ideas. I think the engine is a '78 or '79.

 

[Chum Slick]

Re: 70 HP Evinrude sluggish when throttle up

What year is the 70 Johnson? Sounds like gummed up carbs. The oil plug with the longer tip goes on the bottom. The longer tip should be a magnet that attracts metallic particles in the oil.

 

[Chum Slick]

Re: 70 HP Evinrude sluggish when throttle up

My bust about engine year. Didn't notice the 78 or 79 at end of post. Too early in the A.M. If you engine is a three cylinder with three carbs, check carbs. I have three 70 hp Johnsons from 75 to 79. Great little engines but carbs are prone to gum up if not cleaned yearly.

 

[mnmfors]

Re: 70 HP Evinrude sluggish when throttle up

compression check?<br />I have an 85 115 merc that ran great after it was on a plane and at an idle. I did a compression check and it has none in #3.