motor randomly lost power while running across lake

[river-life]

i have a 90's modle 25hp 2/s mercury. while running across lake at full throttle engine started dying/losing power. it never cut off and would start back up with no problem. got the boat home and next day started the engine in the yard and at half throttle and up exhaust pops then recovers then pops and eventually chokes out and shuts off. when trying to restart its hard to start. rebuilt carb and new plugs it started right up but still has the exact same symptoms. can anybody help?

 

[gm280]

Re: motor randomly lost power while running across lake

i have a 90's modle 25hp 2/s mercury. while running across lake at full throttle engine started dying/losing power. it never cut off and would start back up with no problem. got the boat home and next day started the engine in the yard and at half throttle and up exhaust pops then recovers then pops and eventually chokes out and shuts off. when trying to restart its hard to start. rebuilt carb and new plugs it started right up but still has the exact same symptoms. can anybody help?

First of all welcome to iboats :welcome:

Did you rebuilt the carb after it shut off running across the lake...? Also, is your fuel pump working properly. It sounds like the engine could be starving for fuel and going to a lean run and then shutting down. Check your fuel pump and primer bulb as well. If those are working well, then you still have a carb problem. Next time it starts to pop and shut down try the choke to see if it goes back up again. If so, you need to clean the carb again...

 

[river-life]

Re: motor randomly lost power while running across lake

thanks. yes rebuilt carb after the runnig issue. ive not checked the fuel pump but bulb seems to b working fine. ill give the fuel pump a shot. thanks again for your help.

 

[river-life]

Re: motor randomly lost power while running across lake

wait? where would the fuel pump be located? sry im a complete newbie when it comes to outboards.

 

[river-life]

Re: motor randomly lost power while running across lake

Got home from work and found a fuel line that was melted and gooped up on the inside. New fuel lines in the am hopefully that's the issue with the fuel delivery.

 

[river-life]

Re: motor randomly lost power while running across lake

Replaced fuel line and it didn't fix it. Pulled spark plugs and noticed that the plugs had gotten extremely hot considering the metal was tarnished. After removal I noticed the bottom cyl plug had welded itself together. There was no longer a gap or electrode just a glob of metal. Well replaced the plugs it fired right up no exhaust pop but would run for a min or so then cut off. Then became hard to start. Got it running again and noticed water leaking out side of engine. I'm expecting the worst guess ill do a compression check to verify.

 

[river-life]

Re: motor randomly lost power while running across lake

so after a little research the water is leaking around the exhaust gasket. still no compression test. big concern is why the spark plugs got so hot that one welded itself together. really need some help guys. praying that the motor isnt trashed.

 

[glenn property of pam]

Re: motor randomly lost power while running across lake

i would surgest that you stop running the motor until you can figure out what the problem may be. It sounds like the carb on the cylinder with the melted plug is running lean and that will cause heat. Do the compression test then go back to post #2

 

[river-life]

Re: motor randomly lost power while running across lake

After fiding the water leak I stopped the engine. The fuel pump is made into the carb so was rebuilt with the carb. Its possible that the gas was bad still had some gas from last yr in the tank. Maybe water and ethenol causing lean mixture? Water pump maybe?

 

[carholme]

Re: motor randomly lost power while running across lake

If it was mine, I would stop immediately before further damage is done. Remove the covers to gain access to the pistons and see what they look like as well as the rings and cylinder walls. The problem may have begun with a lean carb but your description of the sparkplug indicates that there is probably damage inside that cylinder.

What is your engine s/n?

Gerry

 

[river-life]

Re: motor randomly lost power while running across lake

Do u think I should remove the covers before a compression test? Vn 0G872774

 

[river-life]

Re: motor randomly lost power while running across lake

Pulled exhaust cover bc that gasket was leaking anyway. Found the top cyl to b perfect. Bottom cyl piston and cyl wall scored up. Not ruined but def needs rebuilding unfortunately. Now time to make a decision. ..

 

[carholme]

Re: motor randomly lost power while running across lake

Your s/n comes up as:

MERCURY - ( 25 H.P. (1999 ))
Serial No: 0G872774 Model No: 1025211VD

Parts List for model 1025211VD:

(20/25/JET 20 SEAPRO/MARATHON 15XD SUPER 15/JET20) (2-STROKE) - Mercury, Mercruiser, Force, etc. Parts Lookup

The service manual for your engine is P/N 90-826883 and if you send me a PM with your email address, I can send you a copy in the morning.


Gerry