Water pump and maintenance questions

[CLL2437]

I am about to get my project boat in the water for first time since I bought it 6 months ago. The boat has a 1988 Yamaha 90 on it. I want to make sure that I have a safe and fun outing the first time. The water pump sprayed a strong stream out the back when I tested it the first time on the water but I want to replace it any way. I am about to order a lot of parts I need from Boats.net and would like to get all the parts I need the first time. I was looking at the parts page and there looks to be a lot of parts for the water pump. Is there a water pump kit that comes with everything I need or do I have to order piece by piece? What is the chrome water pump kit for.

Lastly what other maintenance should I perform on the motor and what does pressure testing the lower unit mean?

[Ken]

CLL,
Just order the regular water pump kit for your outboard - unless you are running your boat mainly in shallow water and are picking up a lot of mud/shell. Your question about the chrome kit is a good one - I could not get a good answer from boats.net myself, as to why the chrome kit was less expensive than the regular kit, so I ordered the regular kit. It will have everything you need in it to do a water pump repair.
If you don't already have one, get yourself a Yamaha shop manual - it will pay for itself.
I would not worry about a lower unit pressure test. Just drain the lower unit oil, and replace with recommended oil per owner manual. Look at the old oil for any signs of water intrusion. If you find any, then you will want to do a seal replacement.
If the motor has never been decarbonized, do it. Replace spark plugs. Run the motor - if it performs well, you are good to go. If not, then probably a carb overhaul is in order.
Good luck,
Ken K

[CLL2437]

Thanks Ken,

The the owner rebuilt the carbs a week before I bought it and it ran great when I tested it on the water. How do you decarbonize the motor?

[Ken]

CLL,
Two strokes build up a lot of carbon internally and need to be de-carbonized by doing a "shock treatment" with a detergent like Seafoam.
I like to do the shock treatment once a year on my C115 - in late winter when I am going thru my list of "spring make-ready".
If you use a detergent like Yamaha Ring Free all the time in your fuel tank, then the carbon buildup is not as bad. Still, a lot of 2-stroke owners will de-carbonize once a year - you will get various opinions on this.
I "shock-treat" my C115 by running the following mixture thru it. This will smoke up the area pretty good, and leave a lot of carbon on the drive way:
16 oz can Seafoam
3/4 gal gas
3 oz oil (2 if oil injected)
Disconnect the fuel line at the input to the bulb and attach a three foot piece of fuel line to the bulb. Mix the above in a small container -
I use an empty 5 quart oil jug. Set the container on the deck of your boat and insert the fuel line and secure to make sure the end stays on the bottom of the container. Pump up bulb and start outboard with earmuffs and water hose, of course -run a little above idle for 15 minutes and turn off. Let sit for 15 minutes. Run again for 15 minutes. Let sit 15 minutes. Repeat until all mixture is consumed. Reattach main tank hose to bulb and run regular fuel/mixture thru motor for 10 minutes - you want to get the concentrated detergent out of the fuel system.
Now, clean up the drive way before your wife sees all that nasty carbon and makes you get rid of your boat.
Good luck,
Ken K