evinrude 25hp runs and stops

[robert53a]

Hi, I have a perplexing problem. I have a 1991 evinrude 25hp when I start the motor it runs fine at Idel when I take off aand go to full throttle the boat comes up on plane and the motor will run fine for about 30 to 45 secounds and them totally loose power and cough and chug untill I pull back the throttle to idel it then stabilses and will run fine at idel for a while. If I put around at idel for 5 minutes I can go to full throttle for another 30 seconds before it looses power again. I first thought it was a fuel delivery problem and rebuilt the fuel pump and rechecked the setting in the carb, but it still doing it. any thoughts would be much appreciated. Thanks.....Robert

 

[Joe Reeves]

Re: evinrude 25hp runs and stops

If you have someone pump the fuel primer bulb, acting as a manual fuel pump, does the problem cease to be?

Also, when this takes place..... does the fuel primer bulb have a tendency to be drawn down, as if going flat?

 

[robert53a]

Re: evinrude 25hp runs and stops

Hi, the bulb was pumped and doesn't go flat and it still goes dead. Could this be some kind of electrical problem?

 

[F_R]

Re: evinrude 25hp runs and stops

Possibly, but it sure does sound like a fuel delivery problem. The gas isn't getting into the carb as fast as you are consuming it. You have eliminated the tank and hose and fuel pump, at least so it seems. So that leaves the carburetor. Could be a chunk of something blocking full flow through the inlet needle & seat valve. Or could be the float drop is not correct. Hard to say without looking.

 

[wavrider]

Re: evinrude 25hp runs and stops

Dirty carb or fuel pump or sucking air in the fuel line.

If the needle valve is dirty it will not allow enough fuel to flow in the bowl to allow the engine to run at WOT
If the fuel pump is weak it will not pump enough gas to allow WOT
the bulb can still be hard and not allow enough gas into the carb
If you have air getting sucked intot he fuel line at higher rpms it will not allow the fuel pump to pump enough fuel into the carb.

I would inspect all fuel lines for cracks, remove hose clamps cut line back a few inches and re install

If this does not fix it then fuel pump rebuild/replace

If it still is not fixed then clean/rebuild carb

 

[robert53a]

Re: evinrude 25hp runs and stops

Hi, I pulled the carb again and cleaned and rechecked everything again. I did set the float drop to the maximun 1 5/8" total It was at minimum of 1 1/8". I reassymble and stared the motor it ops check normal. I'l have to go or a boat ride to check out full throttle. Thanks

 

[robert53a]

Re: evinrude 25hp runs and stops

OK test number 4 on this motor gave me the same result. It runs fine for a while and cutout to idle. I have completely replace the entire fuel system and it is not the problem. It's over heating and the temp switch is doing it's job and puts the motor in limp mode. (confirmed by unplugging the sensor wire and the motor will go to wot OK.) what am I looking at? Do I need a new thermostat or sensor? I'll put a infared thermometer on it and see if it is getting above 140 deg. Any help would be appreciated. Thanks.....Robert