1977 70hp 70el77s power loss

Gone_Fishin_

Recruit
Joined
Apr 28, 2011
Messages
2
Hello,

I am having problems with my 1977 70hp Johnson, we have placed a jet pump on the motor and are having problems when we throttle up, it is not pushing properly and not getting the boat on plane. The pump is set at the correct height and there is no cavation problems.

Previously had the same motor on the boat and cracked the block. Bought another motor but was in a fellows garage for 5 years. Started really nice runs good no idle problems, pushes boat really good at idle but when you throttle up it does not move the boat like it did before.

Compression test showed 115 in all 3 cylinders. Not sure where to look or what to look at. Have re-built the entire jet, replaced seals, bearings and placed shims correctly.

Carb problems? power pack problems? not sure, if anyone can give me some idead to what to look at or replace would be greatly appreciated, still have other motor with cracked block so have all parts we need.
 

Big flop

Petty Officer 1st Class
Joined
Apr 6, 2011
Messages
290
Re: 1977 70hp 70el77s power loss

Check spark.
After sitting for 5 years I would
Clean and kit carbs.
 
Top