Will not get to full power under load...

WE have a 90HP 2 Stroke 2002 Mercury Outboard, we used the boat for a couple of years then we didn't use it for about 5 years, but we always took care of it even when we didn't use it... WE fogged it for winter time and always burned out the fogging stuff in the spring time and put stabilizer in the fuel...

We decided to take the boat out for a spin to go fishing this year and It worked GREAT until we started it up for the 3rd time to move to another bay...

When we tried getting it up to speed by pushing the throttle to WOT, it would only get up to about 3000 RPM when normally it goes to approx 5000 RPM's at WOT!!

now we could get it up to WOT if we babied it and hit the choke a few times...

Now if we put the throttle into idle mode and revved the engine, oh wow it would rev up EXCELLENT, but under load it was very sluggish?? It also worked great in max reverse too, so this is definitely confusing!!

It only acts up when its under load going forward!



Any ideas would be GREATLY APPRECIATED on how to cure the issue...

WE have tried replacing the spark plugs but it didn't help any...

PLEASE HELP!!!

Re: Will not get to full power under load...

Maybe the fuel pump diaphram needs to be replaces- cheap and easy to do.

Re: Will not get to full power under load...

An engine will rev to the moon in neutral even if it is running on one cylinder. And please stop doing that. If pushing the key in (that's a primer, not a choke) helps, then you need to rebuild the carbs. Continue running the engine under a lean condition will destroy it. After you do that, add fuel stabilizer and run the engine long enough to get the mixture into the engine before you store it.

Re: Will not get to full power under load...

Silvertip said:

An engine will rev to the moon in neutral even if it is running on one cylinder. And please stop doing that. If pushing the key in (that's a primer, not a choke) helps, then you need to rebuild the carbs. Continue running the engine under a lean condition will destroy it. After you do that, add fuel stabilizer and run the engine long enough to get the mixture into the engine before you store it.

Click to expand...

Ok you dont have to get pushy about your answer, my father the one who owns the boat was a repair person on snowmobiles and has carb experience... He knows all the do's and dont's about an engine...

I am am not trying to be mean but your reply did sound a little snappy at me... All I was doing was trying to seek advise...

Now the lake we were on is 15 miles long and the boat dock is near the end of it when we were on the other side of it... Going at the speed we were going without babing the motor we would have been all night trying to get back to the main dock...

We dont intend on taking it out again untill its fixed...

Dont be so snappy PLEASE...

Re: Will not get to full power under load...

???

Re: Will not get to full power under load...

Stabilizer only works for an off season. Five years without using or draining the old fuel and replacing with fresh fuel, and adding stabilizer every year hasn't really done anything for your carbs but accumulate more gum and varnish.

After Dad is finished cleaning the carbs, do your motor (and carbs) a big favor and drain all the old fuel, start with a clean slate.

You'll all do fine.