three questions

[sherwin]

I have three questions concerning my Yamaha 9.9 four-stroke outboard.

First concerns possible overcharging from the alternator and what to do about it.
The alternator has a max output of 10 amps. Even feeding a bank of two wet-cells
in parallel, that's a lot of current to feed in over an extended time. The batteries get
up to 14 volts and possibly higher. Will this high charge rate hurt the batteries, although
they will build up resistance as they charge up? Would there be any damage to the alternator if it
were disconnected from the batteries at any time?

Second question concerns the susceptibility of this engine to develop blocked jets
in the carburetor. Although I have and inline filter from my tank and another filter
in the engine fuel line, I had to clean the jets today after doing the same job a month
ago. Although I did not use the engine hardly at all in the interim, I was made sure
to run it for a few minutes every week, but it got progressively worse. My gas is typical gasohol, which I bought the beginning of the season. About mid season I added a carburetor cleaner and gas preservative to the main gas tank. Both my filters do not look very dirty. Pulling the carbs and cleaning the jets is a half day job,
so this is getting a bit tedious. Maybe they will someday design a carburetor with a built-in cleaning mechanism, like a needle plunger which can be operated without pulling the
carbs.
Seems like these types of carburetor problems are almost an epidemic, as engines are lined up at my mechanic for this same problem. Four strokes are
especially susceptible to this problem because of their fine diameter jets. Any ideas on how to minimize this problem?

Last question is about throttle handle behavior. When increasing throttle with the handle control,
my engine does not react immediately and then it
reaches a point where it increases quite a bit with just a small turn of the handle. I can then
back off to try and find a good speed. Should there not be a smooth increase of engine rpm as the handle is turned?

[Ken]

sherwin,
Best not to charge your batteries in parallel - get yourself a battery switch. Use a common ground between the batteries, and use the switch to select either bat 1 or bat 2. Do not switch the batteries when the motor is running - you can damage the alternator that way .
The alternator can deliver a max of 10 amps - it has current and voltage limiting circuitry built into the regulator. It should charge a battery, one that is in good condition, up to approx 14.6 volts max. A charge rate of 10 amp is not a high charge rate for a typical marine battery.
If all of your filters are doing their job, your carb jets should not be getting clogged up that often - you might consider adding an in-line Racor see-thru water separator filter. Also, sounds like you may be getting contaminated fuel from the pump - may want to try a different source.
For your throttle problem, I would look at the linkage to the carbs and observe when you turn the handle. If that looks ok, then I would suspect gummed up carbs - tear down and install a carb kit.
Good luck [img]smile.gif[/img] ,
Ken K

[sherwin]

Ken, thanks for the feedback.

I do have a battery switch. I'm curious as to what the problem is for charging the two batteries while connected in parallel. Won't the charge be equalized between the two batteries, going mostly to the lower charged battery?

I assume you were directing all you comments to my model Yamaha. I have seen no indications of any regulation of either voltage or current output from my alternator. Are you sure there is a regulator on this engine?

If I have cleaned the jets and the float bowl, what else needs to be cleaned or replaced in the
carburetor? What kinds of parts are included in these carb kits?

Sherwin

[Ken]

Sherwin,
If the two batteries in parallel were identical, then there would be no problem to recharge them. But, in the real world, there are no two identical batteries, and one will always be pulling the other down, a little to a lot.
Let's say one of the batteries develops a shorted cell and it's voltage drops to a nominal 10.5 volts - the other battery will be pumping current constantly to the bad battery because the voltage cannot "equalize" until the good battery is pulled down to a damaging level.
If you have only one battery in the charging circuit, then you can monitor the voltage and determine the condition of the battery - if you have two in parallel, you don't know the condition of either.
You can put batteries in parallel in an emergency when one alone won't crank the motor - you are adding the current delivery capacity of each, but even this won't work if one battery has a bad cell and pulls the other battery down.
If you are trying to keep both batteries charged with the 10 amp alternator of your motor, you can either switch them after the other has reached full charge manually (with the motor off) or you can install something like an electronic charger that has monitoring capabilities (like Stealth Technologies) that will automatically switch form one battery to another using the same charging source.
I am curious what you are trying to do with two batteries? Does your model outboard have an electric starter or is it pull-to-start?
No, I was not directing my comments directly for your outboard - I am not familiar with it. I was commenting in general for alternators on outboards. I can't imagine an alternator on a motor and it not have regulating capabilities. Are you monitoring the voltage of the batteries during charging by the motor alternator?
Go to the diagrams in the on-line catalog (above)for your outboard and see if it has a regulator. I would check it for you, but I don't know the exact model number.
What mix of gasohol are you using? E-10? E-15?
Maybe the ethanol is attacking the seals and gaskets in the carbs - that's why I would tear down the carbs completely and examine every piece.
The carb kit will have all the gaskets and seals you need - I think the parts catalog will show you what's included.
Where are you getting your fuel? Again, I mention this because it sounds like you may be getting contaminated fuel from the source pump.
Let us know what you find out.
Ken K [img]smile.gif[/img]

[sherwin]

Ken,
I have a 2002 Yamaha T9.9 High Thrust Four Stroke.

As regards batteries, I don't like to do a lot of
switching between my two batteries, so I keep them in parallel so that they charge up evenly. If either of them go bad, I would see that as a voltage
drop on my voltmeter, and do further checking.
I did have a problem rerouting my alternator positive lead to have it pass through my ammeter.
What I noticed was a big drop in cranking power, which I attribute to large resistance somewheres in this circuit through the ammeter. When I returned the alternator positive lead to go directly to the battery, the normal crnaking returned. I will probably have to debug this later, but I can still monitor the alternator output somewhat with my voltmeter. I still think
the alternator on this engine is unregulated.

As concerns gas, I am probably using what you call E-10, as the pumps say 10% alcohol. I am using the low octane from a Shell station off a busy interstate, who claim they get fuel deliveries almost daily. I have had someone tell me to not use gas older than 60 days, and to put
stabilizer in any freshly purchased gas. My gas was purchased the beginning of the summer, and a
few weeks ago, I put in SeaFoam to both clean the
carbs and stabilize the fuel. My tank and filters
look clean, but I think these four strokes need only a small amount of dirt to block up the jets.

As regards the trottle, this engine only has about 20 hours on it. I noticed the linkage seemed ok, with just a little slack at the very start of turning the handle. My problems occur
closer to half throttle when it is hard to set the
correct speed for the engine, as it seems to over-
shoot as the handle is turned to accelerate or decelerate.

I really don't suspect worn or defective parts
in the carburetor, but tearing it down and rebuilding is always an option. If it is the gasahol, that is a big problem, because that is all they sell here in Wisonsin and Illinois. Gasahol has been around for years. The car manufacturers have long ago addressed these issues. Hard to believe that Yamaha did not follow suit.

[sherwin]

Had a very successful test cruise with my boat. First time on the Great Lakes since we left 30 years
ago for the sunny (except for hurricanes) south.

Seems like my cleaning of the Yamaha jets for the second time produced some results. The engine did not skip a beat, and ran good at all speeds for about one hour. This was done without changing the
gas, or adding anything more to it. Certainly, running an engine for an hour can do wonders for it
when it has only been run for occasional 5 minutes
once a week. I am going to pay more attention to
using stabilizers, and keeping my filters clean.

I still don't have any good answers to connecting
my ammeter to the engine alternator, but that is a
low priority concern for me. I am also concerned
about storing the engine for this winter. I will
probably run the engine dry, and open the carburetor drain plug. Can anything else be done to keep the jets and float bowl clean for the winter?