Couple Boat Questions

[woody1975]

OK - Finally got the boat out on the water this weekend.

Here is what I got -

1995 75 HP Mercury on a 16.5' Alumacraft Dominator

Here is my issue.....

1) The boat really dogs out of the hole!

2) Once I get it going a little bit and think it is going to finally jump up on plane, the motor whines out (Almost seems like it is cavitating)

3) Once I do get it up on plane, rpms run about 6500 and even get close to 7000 when I nail it.

Just before we left, I opened the motor and noticed that two of the three spark plug wire were barely hanging on the spark plugs. I put them back on. I never got a chance to run the boat after this, so I am not sure how it will run now.

My question is did the spark plugs fix any of my issues and do I need a new prop?

Thanks for any help.

DL

[Ralph Wiggum]

When it dogs out of the hole, is the motor revving?

Kind of sounds like a spun hub in your prop.

[woody1975]

Yep - It revs really high and then I need to ease into it - Takes it a while then to get on plane.

What does that take to fix?

How much?

[Valv]

6500 to 7000 rpm are way too high for that motor, I would not go that much, stop at 5500 or 6000 max.

As Ralph noted check the hub, but having 2 cylinders not plugged in might be the issue.

[Ralph Wiggum]

What does that take to fix?

How much?

If it's spun, a prop shop would be able to put a new hub in for $50 or so. Or you could buy a new prop.

[marine_man]

I definitely agree with Valv - 6500 to 7000 for rpm is way past where you should even remotely be... try and keep it lower than that.

It might be a spun hub - use a paint marker or some white out and draw a line from the outer part of the hub to the inner part (where the splines are) across the rubber. Go out and run it and then check the paint mark - if the marks aren't in a line anymore the hub is the problem. As Ralph said, you can have the hub replaced at a prop shop or buy a new prop.

marine_man

[woody1975]

Thanks alot - I appreciate the help!

DL

[Ralph Wiggum]

It might be a spun hub - use a paint marker or some white out and draw a line from the outer part of the hub to the inner part (where the splines are) across the rubber. Go out and run it and then check the paint mark - if the marks aren't in a line anymore the hub is the problem. As Ralph said, you can have the hub replaced at a prop shop or buy a new prop.

Brilliant!

[woody1975]

****UPDATE****

Recently returned from the AYA Tournament on Little Pine in Perham.

Plugged the Spark Plug wires in and she runs a lot better. I have good hole shot and she is on plane right now. With the throttle pinned, she is running right around 5600 RPM. The only problem I am having now is that it is missing every once in a while. It usually doesn't do it until I have been running it for a while and then all of a sudden it will spit and sputter like it is going to kill and then keep on purring. Any one have any ideas what is happening here? Bad plug somewhere in the line????

Thanks again,

DL

[BoxMN]

Might try the easy tings first - new bulb and/or fuel line. Just to make sure it is not sucking air. Fuel filter (probably not likely). Maybe even water in the gas?...

Good luck,

[marine_man]

Ignition or Fuel - could be water in the tank, could be an intermitent ignition problem. Start with the fuel -it's easier to troubleshoot. Pump some fuel from the tank into a clear bottle / container and let it sit for a little bit - see if there's water in the bottom.

marine_man