10mph at WOT 99' 25hp

[healey8390]

Working in my friends boat and I'm stumped. He has a Carlolina Skiff J16 and was getting 18mph by himself at about 4500-4700 rpm. I believe the pitch is too high,13p. But it got up on plane etc...

Boat will only hit 10mph now with just him. It doesn't bog, chug, or sputter. It's smooth, it's just "all it has". Compression is 130 x 2. Spark jumps 7/16 x 2. Link and sync is good. I also checked the fuel pump diaphragm and it doesn't have a tear/hole... I rebuilt the carb about six months ago due to flooding/ball not getting hard and It ran fine. I am stumped! It idles great and will rev up in neutral. I'm starting to suspect am exhaust leak be it the base or side cover. How do I check this? Also, the water coming out of the midleg is piping hot! Not sure if that's normal on this engine. Open to all suggestions, thanks for bearing with me and TIA!

 

[tphoyt]

Maybe time for a water pump service.
If it’s overheating it will lose some power.

 

[healey8390]

I can't believe that I left out the most important piece of information, I guess I was really tired. He got an overheat alarm at idle the two trips prior to this happening? Can a head gasket leak water when compression is good?

 

[racerone]

Heard the overheat alarm and did nothing about it ??

 

[healey8390]

He "said" he turned it off right away and afterwards it cooled down it ran fine and was pumping. The next trip is when it was really slow and the alarm went off when he got back to the boat ramp. He said it was pumping fine.

I did the above checks on it Monday, it's pumping fine but on muffs it's obviously getting watere forced through it. I'm not sure what the next diagnosis step is? Thank you.

 

[racerone]

Post the actual compression values.----If good then install a new impeller.

 

[healey8390]

Post the actual compression values.----If good then install a new impeller.

130psi x 2.

 

[healey8390]

We took it out today, the tilt pin was too high. With me it got up to 18.8mph...

It is going to need an impeller though. The buzzer came on when I got back to the dock when it was idling for a few minutes.