Outboard Motor Basics

I removed the engine covers and for the most part have no idea what I’m looking at.

Regrettably, you've hit the nail right on the head. These new engines need to hook into the "Mother Ship's" computers to even tell WTH is going on. You've got 2 big "Kids, don't try this at home" engines on your transom.

There is little you can do on the water beyond pulling the cowl and scratching your head, especially when you're out on the water. I keep a pretty nice tool kit aboard the boat, however, few things are specifically for the engine, those being "an emergency pull cord" (115 supposedly could be started by hand), a fully-charged battery pack to avoid even trying to start it by hand, and a piece of copper wire to ream out the "P-tube" outlet when it's blocked so I can be sure the water pump is working.

The only "repair" I've been able to do is a very simple one, replacing the cowl tilt/trim switch which stopped working for "Down", a very easy, 15 minute job. YouTube helps with many small tasks, but most involve hauling out. This was one of the few that could be done at the dock.

BTW, don't forget Yammies are metric...

Now the lecture, the inability to do things clearly demonstrates why you need to keep up with all maintenance done by a qualified technician who has access to all the special tools and the Mother Ship Computer, and to sin on the side of precaution. No matter what, I have my water pump, internal sacrificial zincs, thermostat, etc. replaced every fall during winterization. Even routine winterization should be done by a pro with the computer. Yes, I could change oil/filter, grease things, fog it, etc., but without hooking it up to the diagnostic computer you wouldn't know if there were any readings that might suggest an impending issue.

One other suggestion. Don't forget to pay your SeaTow premium.

hey Matt. good luck with the new ride! there's not a lot you can do at sea on those motors. they're a bit sophisticated for the average guy. and as stated by others, without a computer its very hard to determine what's wrong. one little piece of advice that's very simple. replace your spin ons every 50 hours (and carrying a spare for each motor). those 300's are historically good motors, but they are -like all 4 stroke outboards- they do require clean fuel. don't worry too much, there are two motors back there which should give you piece of mind

they do require clean fuel.

Yeah, DUH!! Forgot to mention Startron IF you use normal fuel w/ethanol. I used to use it religiously and still do in my lawn mowers.

I bit the bullet 2 years ago when the local service stations started carrying ethanol free premium gas, yeah I can hump fuel down to my boat. Yeah it hurt in the wallet, but for longevity of all parts of the fuel system and the engine, I see it as a "Pay me now or pay more later" scenario...

probably goes without saying...basics and always a good reminder
startron yes max it out on each fill up as Dom said or use seafoam
flush each engine for 10 minutes with fresh water after every run everytime
when getting on plane and on plane, trim the engines and trim tabs accordingly to conditions and your speed
check oil level regularly keep over half full for each engine at all times

my 2c from running twin 225 mercs

Agree 100% with the Startron. I had my Johnson 2 stroke 200 HP outboard for 12 years. Used Startron religiously and never had a problem. The guy I sold the boat to still has it 11 years later and the motor is still humming along.

Regrettably, you've hit the nail right on the head. These new engines need to hook into the "Mother Ship's" computers to even tell WTH is going on. You've got 2 big "Kids, don't try this at home" engines on your transom.

There is little you can do on the water beyond pulling the cowl and scratching your head, especially when you're out on the water. I keep a pretty nice tool kit aboard the boat, however, few things are specifically for the engine, those being "an emergency pull cord" (115 supposedly could be started by hand), a fully-charged battery pack to avoid even trying to start it by hand, and a piece of copper wire to ream out the "P-tube" outlet when it's blocked so I can be sure the water pump is working.

The only "repair" I've been able to do is a very simple one, replacing the cowl tilt/trim switch which stopped working for "Down", a very easy, 15 minute job. YouTube helps with many small tasks, but most involve hauling out. This was one of the few that could be done at the dock.

BTW, don't forget Yammies are metric...

Now the lecture, the inability to do things clearly demonstrates why you need to keep up with all maintenance done by a qualified technician who has access to all the special tools and the Mother Ship Computer, and to sin on the side of precaution. No matter what, I have my water pump, internal sacrificial zincs, thermostat, etc. replaced every fall during winterization. Even routine winterization should be done by a pro with the computer. Yes, I could change oil/filter, grease things, fog it, etc., but without hooking it up to the diagnostic computer you wouldn't know if there were any readings that might suggest an impending issue.

Thank you, a battery pack is on my list to have on board for emergency starts issues. I ASS-use that P-tube thing you are talking about clear8ng with a piece of wire is that “piss stream” that exits the motor when running???

All work on the motors will be done by an authorized Yamaha Service.

One other suggestion. Don't forget to pay your SeaTow premium.

Already have Sea Tow thanks!

Yeah, DUH!! Forgot to mention Startron IF you use normal fuel w/ethanol. I used to use it religiously and still do in my lawn mowers.

I bit the bullet 2 years ago when the local service stations started carrying ethanol free premium gas, yeah I can hump fuel down to my boat. Yeah it hurt in the wallet, but for longevity of all parts of the fuel system and the engine, I see it as a "Pay me now or pay more later" scenario...

I’ll be fueling only with non-ethanol which is sold at the marinas down here. I have been advised to use an additive, Yamaha Ring Free as well.

hey Matt. good luck with the new ride! there's not a lot you can do at sea on those motors. they're a bit sophisticated for the average guy. and as stated by others, without a computer its very hard to determine what's wrong. one little piece of advice that's very simple. replace your spin ons every 50 hours (and carrying a spare for each motor). those 300's are historically good motors, but they are -like all 4 stroke outboards- they do require clean fuel. don't worry too much, there are two motors back there which should give you piece of mind

Thank you, question, what are “spin ons?”

Thank you, a battery pack is on my list to have on board for emergency starts issues. I ASS-use that P-tube thing you are talking about clear8ng with a piece of wire is that “piss stream” that exits the motor when running???

All work on the motors will be done by an authorized Yamaha Service.

Yes, Yamaha actually calls it a “P Tube”, was ROTFLMAO when I learned that!!

Thank you, question, what are “spin ons?”

Fuel - water separator?

Good on you Matt !!. Yes all the above plus the Yammy ring free. It's required by Yamaha.

I’ll be fueling only with non-ethanol which is sold at the marinas down here. I have been advised to use an additive, Yamaha Ring Free as well.

Yammie Ring Free also a good idea, especially if you do a lot of low RPM running like I do because I'm fishing in estuaries. It sure isn't cheap. I stick it in once every 150 gallons...