25 hp Evinrude nearly dies at high speed

[tccard]

My 1990 25 hp Evinrude will run fine at high speed, and then suddenly while on plane lose all power and revert to idle speed (i.e. as if fuel only going thru low speed jet). Then after shifting several times from neutral to forward, it will again run fine for several more minutes until the same thing happens. I have cleaned fuel filter, changed fuel tank and fuel line/bulb....no help. Could it be a piece of crud which is periodically clogging the high speed jet? If so, is there an easy way to clean it out? Thanks for any advice you can give.

 

[Cofe]

Re: 25 hp Evinrude nearly dies at high speed

Sounds like your motor is overheating, causing it to go into SLOW mode.
Do you have a good stream of water coming out of the telltale?

By the way, Welcome to I Boats Forum!

 

[xbassman]

Re: 25 hp Evinrude nearly dies at high speed

That IS the first thing to see if you are getting hot...checking the pee hose is a good idea. Those mud wasps love to make a home in there! (no pee, run a piece of wire up the hose...sometimes that works) Next, check your primer bulb...is it pretty hard while running? If not the check valves inside your bulb may be failing. I know your vent is OPEN on your portable gas tank during operation! My 90 25hp Johnson had a high speed jet problem. Where it is located (on my carb) in the bowl right behind the bowl drain plug is where all the sludge ends up. On my carb I only had to unscrew the drain plug, put a screwdriver in the hole and go back a couple of inches, unscrew the high speed jet (it will come all the way out), then hit the area with a quality carb cleaner, cleaned the jet, back in, bowl drain plug back in and off I went. If you find a lot of crud in the jet, I would rec. a carb teardown.

 

[Cofe]

Re: 25 hp Evinrude nearly dies at high speed

My 90 25hp Johnson had a high speed jet problem. Where it is located (on my carb) in the bowl right behind the bowl drain plug is where all the sludge ends up. On my carb I only had to unscrew the drain plug, put a screwdriver in the hole and go back a couple of inches, unscrew the high speed jet (it will come all the way out), then hit the area with a quality carb cleaner, cleaned the jet, back in, bowl drain plug back in and off I went. If you find a lot of crud in the jet, I would rec. a carb teardown.

On this year of motor, the high speed jet is behind the the lower hose connection on the front of the carb bowl. If you remove the jet, use a proper jet removal tool. The jet can be easily damaged!

If the telltale line is not plugged, suspect the water pump, and the water tube rubber gromet may be melted/damaged as well. I have this same year/model outboard as you.

 

[tccard]

Re: 25 hp Evinrude nearly dies at high speed

Thanks guys. Motor seems to have a good water stream like it always has(the occasional cough), fuel line bulb is firm and vent is open on tank. It actually has a new tank, fuel line and bulb, which has not helped the situation. To be sure I'll verify good water stream, then move on to removing and cleaning high speed jet and area around it.

 

[Cofe]

Re: 25 hp Evinrude nearly dies at high speed

Thanks guys. Motor seems to have a good water stream like it always has(the occasional cough), fuel line bulb is firm and vent is open on tank. It actually has a new tank, fuel line and bulb, which has not helped the situation. To be sure I'll verify good water stream, then move on to removing and cleaning high speed jet and area around it.

Keep in mind that a motor can still be overheating even if it has a good water stream. The thermostat can be stuck closed, or in the case with mine, a piece of water pump impeller stuck in the hole. If you feel the head is getting over 145 degrees, chances are the stat is not working.