Help needed for a total rookie

[aka Fleck in OH]

Hello folks, I'm a total rookie to outboards and pretty much any boats in general. I'm a veteran motorcycle rider so I have a decent grasp on engines and I do all my own maintenance, but I'm not a serious wrench.

My family has a pontoon boat on a 900 acre lake in Michigan--this boat belongs to my mom. She and her husband bought it in the very late 80's and her husband has since passed away and took with him any knowledge of boats & motors. Every year at the end of the season, she pays the local marina to pull the boat from the water and store it, and return it in the spring. Other than to stabilize the fuel, I don't think the marina does a damn thing to the boat or the motor.

The motor is a 70 HP 3 cylinder oil-injected 2-stroke. Now I've read back 8 or 9 pages of threads in this forum to try and pick up a little, and I'm guessing that it's an '86 or '87 model. The boat/motor purchased from a bank as a repo.

I'm curious about a number of things--first off, what's the RPM range of this motor? There's an LCD tach that reads ~500 rpm at idle, as low as 300 rpm in gear at no-wake speed, and will climb to a screaming max of 2000 rpm, or 2100 if it's feeling ballsy that day. Is this a correct range or is the tach hooked up improperly?

It doesn't run as well these days as it has in years past, but it does get us around the lake and has never stranded us.

Last weekend, I heard an alarm--I never heard any alarm from this thing before. And by reading threads on this board, I'm guessing it was either an over heat or an oil problem. It was a horrible noise--and when I'd cut the motor and then turn the ignition back to 'on' but with the motor not running, I'd still get the loud alarm.

We'd sit for a few minutes, get restless, start the motor up and get it moving, all with the alarm. After a minute or two running, the alarm would stop, the motor would rev properly once again, and we'd take off and the thing seemed to be running even better after the alarm than it had before hand. The LCD tach has three indicators on the bottom of it, 1 of them seems to be always lit and the other two have never come on. I'd have to see a picture of this gauge to even tell you what the other two indicators look like... one of them was a high temp indicator I think.

Oil level was right up near the top--we keep Yamalube 2-stroke in there.

Any ideas?

Next question is about the prop-- it's stock, came with the motor. As I understand, a new prop would make this whole thing work a lot better... how much could we expect to drop on a decent prop? And how do we choose one? Installation as easy as a pin, nut and prop or more involved?

Regarding the hydraulic lift--it works just fine, but what is the specific purpose of it? Is it simply to get the motor out of the water to keep sea life from growing all over it when not in use? Or are we supposed to lift the motor just a little from bottom when running the boat, to change the prop angle?

Like I said, I know next to nothing or perhaps just enough to get myself in to trouble. We were putting past a house on the lake when the alarm went off and I yelled to a gentleman on shore to ask if he had any idea what that alarm might be indicating. (He had a Yamaha 90 on the boat docked in front of his place) and he was kind enough to say, "Throw another thousand dollars at it..."

I hope you guys can help a bit more than that guy! Any links for newbies or general 2-stroke outboard info would be appreciated as well.

Thanks much!

[Ken]

Fleck,
First thing you want to do is get yourself a Yamaha shop manual if you are going to be doing any of your own maintenance - it will pay for itself. Go to yamahapubs.com. An owners manual would be helpful also.
For storage, you need to follow the owners manual on fogging the motor and adding fuel stabilizer. The best thing is to run the outboard once a week in off season, but that may not be practical where you are.
I believe the max rpm range for that three banger is 5000-6000. You need a prop with a pitch that will give you that at full throttle and trimmed out.
Your tach is probably bad. Is it an add on or is it as old as the outboard? Check all connections on back of tach and make sure they are tight and no corrosion. Also, some of the digital tachs have switch settings on back to accommodate 2-stroke or 4-stroke. Maybe yours is settable.
The alarm you are hearing is probably from overheating. If the water pump is at least three years old, I would recommend a water pump repair. If that doesn't fix the alarm, then take a look at the thermostats - one or both could be sticking. Also, the PRV could be stuck partially open and dumping cooling water prematurely. Check recent posts for detailed discussion on all of this.
If motor has not been de-carbonized in past three years, it's time to do it.
The power trim/tilt is to trim out the motor when up on plane to maximize attack angle of the boat hull - on a pontoon boat, there won't be much trimming. Also, t/t comes in handy when get in shallow water and when trailering down the highway.
You should be able to get that little Yammie running ok for a few hundred dollars, not a thousand. Don't go to the mechanic that fellow on the lake uses!
Good luck,
Ken K

[aka Fleck in OH]

Thanks for the tips, Ken! I will take a look at the tach and see if there's a selector switch on it--it's been that way since day one. It is as old as the motor and boat, but it's always read no higher than, say, 24 or 2500 RPM. Looks like it just needs to be doubled to be accurate! And it's a Yamaha tach, a round jobbie with a 2-digit LCD readout, x100. There's an LCD bar graph running vertically just to the right of the 2-digit readout.

We'll have to see about getting the water pump looked at when it's pulled for the season and stored. Otherwise, nobody in the family has the resources or know-how to get it out of the water!

I think it runs pretty well considering it's age. Maybe a new water pump and a new prop will make it feel like a kid again.

We have fun looking at all the other pontoons on the lake with 25 and 45 horse motors on them. Of course, there's a number (more these days than there used to be!) of pontoons out there with 90's and up, too. And a whole lot of much bigger boats.

Thanks much for the tips.