1972 Evinrude 25hp power loss

[kfc1188]

I recently purchased a 14' fiberglass boat with a 25hp Evinrude outboard. I am having some problems with power loss at full throttle. Sometimes the engine works perfectly, but other times it only runs at 25% speed. It usually runs this way for a while and sometimes gags and goes to full speed. Does anyone have any suggestions for me? I just replaced the spark plugs, but the problem persisted. I am starting to think that there may be a problem with the carburetor. How can I obtain a breakdown print of the carburetor so I can clean it? Thanks in advance for any help.

 

[Boatist]

Re: 1972 Evinrude 25hp power loss

Kfc<br />Welcome to the board. First thing you should do is get a manual it will save you TIME, PARTS, and MONEY over time. Look on bottom of page for manual.<br /><br />I would make sure have good spark on both plugs, should jump at least 3/8 of a inch. If no spark from one cylinder or weak then time to pull flywheel and check or replace points and condenser for each cylinder. <br />When it is running bad try pulling plug wire off one at a time to see which cylinder it is. <br />Check compression on both cylinders, Shold be even and 100psi. If low or uneven then decarb the engine and see if that helps.<br />When running bad pump the primer ball and see if makes any difference, also pull the choke our a little or for a short time and note difference.<br />By this time should have a idea where problems lies. Follow the trouble shooting in your new manual.

 

[JB]

Re: 1972 Evinrude 25hp power loss

Before you buy a manual, KFC, you need to identify the model number and get the correct year of your engine.<br /><br />Good luck.

 

[kfc1188]

Re: 1972 Evinrude 25hp power loss

I checked the fuel ball and it is full when the motor is malfunctioning. Also, i have tried pulling the choke and it just bogs the engine down. I have even tried adjusting the idle mixture screw (lean to rich) and it doesn't seem to help. Possible clogged jet or stuck float?

 

[Boatist]

Re: 1972 Evinrude 25hp power loss

Kfc<br />Need to check spark and compression and then should have good idea where to start. With what you reported about fuel pressure and choke I dout it is a fuel problem. My wild ass guess is no spark on one cylinder. Your are not going to know until you check spark and compression.