yamaha four stroke problem

[Savage Brewer]

So here is the info I have.

Yamaha 40HP Four Stroke motor

Manufacture date: 2005

Tiller model with electric start, has 3 carburetors.

I bought this in 2008, it has run fine for years. Last time it was out was in November 2011. I changed the oil, plugs and lower unit oil in the fall of November 2011. Tried to run the engine dry before putting it away, but I am sure some fuel stayed in the carbs.

Last year (2012) I sold my home, moved to the Minneapolis area, and then a number of things happened last year where my boat stayed in storage for 18 months...

So today is the first time out with it, did all my pre flight checks over the last couple days, oil, lower unit, you name it. (didnt shange the plugs, because I figured they were fine as I only had one trip on them.

I completely cleaned both fuel tanks (6 gallon and a 3 gallon) and filled with fresh new gas (with Marine StaBil and Yamaha ringfree) and flushed the fuel line and bulb. Fired it up in the driveway a couple times, seems to run ok, a little rough, but I figured once I get out on the water and open it up for a little while it will clean out.

I was wrong, in neutral I can rev the engine, a little bog going WOT but not bad. In gear, couldn't even get above 6 MPH. rough idle, wants to stall out, 25% throttle its kinda ok, but trying to get anything more would cause it to bog down.

So I beached it on some sand I found, and swapped plugs (I always carry a second set, habits from my old two stroke days) The plugs I pulled out were wet, and possibly a little oil residue.

After changing plugs, it still behaves the same.

I think that it is running way rich and is flooding out, but I may be way off too. I just dont have much experience with multiple carb setups, so I am a little nervous about pulling it apart.

So a couple questions, would you think the problem is in the carbs? maybe some varnish caused parts to get sticky and hold open?

If I pull the carbs, do you need to do a special synchronization procedure like when working with multi carb setups on motorcycles? Essentially balancing the cylinders?

Ant thoughts, let me know, I am hoping this is a simple fix, (or hopefully inexpensive one)

Also who would you reccomend for repairing an engine like this? I live in Savage so it would be nice to find someone within 30 miles or so.

Thanks

[h8go4s]

Try spraying carb cleaner in while it's running.

[Savage Brewer]

So here are some shots of the plugs after 1 hour at about 2000 rpm (guess)

Top Cylinder

[Savage Brewer]

Middle Cylinder

[Savage Brewer]

Bottom Cylinder

[Savage Brewer]

One thing that I notice right away is the bottom plug is wet.

I verified all 3 cyl's have excellent spark.

I dont have the proper end for my compression tester for the 18mm spark plugs, so I cannot post that.

I am fairly certain it is a carburetor issue, but thought I would throw up the info for our marine experts here.

Kinda wish I could find a service manual for the motor.

[LMITOUT]

I have to wonder if the carburetor jets aren't slightly plugged after sitting for so long. Even though you filled the tanks with fresh gas there is still some residual gas in the carbs from the last time it ran and they may gum up after that amount of time being unused.

A buddy of mine has a Yamaha T-8 kicker on his boat and it would only run fast enough to troll if the choke was pulled out. It would idle fine without the choke. A new jet and it was good as new again.

Good luck.

[wakeguy]

Tough to tell if I'm seeing the camera flash or real colors but a white plug indicates a lean condition. The most likely problem is plugged carbs. Expect to pay roughly $350-$500 to have the carbs cleaned and a link and sync done.

[Savage Brewer]

Yeah, the top two have white deposits on the ground strap.

But the bottom plug does not, in fact it is wet.

I did find something concerning, dont know if it was affecting me earlier, but the quick disconnect from the fuel line and tank is super finicky.

I might remove the quick disconnect all together on the tank side and hook up the hose solid. Thus eliminating a quick disconnect that in years past has given me problems before.

[leechlake]

I'm not handy enough to fix my motor so I bring it in. It's a 25 4 stroke Yamaha 2008. I think there is something like a low idol jet. If the low idol jet is clogged then it will kill when you're trying to go slow. I'm sure I'm in the ballpark with your potential problem but I don't know mechanic lingo so interpret my suggestion with that in mind.

[Savage Brewer]

Anyone have experience with Dans Southside Marine in Bloomington for service? Or the Boat Doctor Marine down in Montgomery?

Looking like I will have to take it in, Dan's is the closest Yamaha shop to me, but I am willing to drive a bit further to know that the mechanic is going to do a good job and the rates are reasonable.

Hallberg Marine up in Wyoming is the closest Yamaha 5-star shop, but thats a bit of a haul (60 miles each way).

A guy at the ramp recommended Boat Doctor Marine down in Montgomery (about a 30 minute drive). They are not a Yamaha dealer, but it sounds like my F40 was a joint project between Mercury and Yamaha.

Basically I would like to find a service shop I can trust., so any info is helpful.

Feel free to use "PM" to send information if needed also.

Thanks

Thanks

[Spinner1]

Not familiar with your local boat shops. My 2006 60HP Yamaha has drain plugs on each of the 4 carb bowls. Just for your future reference. I open the plugs up to verify I ran the carbs completely dry each fall. Yammies are even more sensitive to fuel problems than other outboards. I see them at the local repair shop and the cause if often bad fuel from resort fuel tanks that sit all winter. You might pull the drains now and see if fuel is getting to all the carbs. I would probably try to get some Sea Foam or other high quality carb cleaner ran through it if I possibly could. I don't think you have much to lose by trying. I know I wouldn't want to drop 500 bucks getting carbs cleaned.

[Savage Brewer]

The guys working on my engine showed me the drain plugs. I hate removing anything from a carb if I don't know what it is there for.

Learned that working on GM carbs, pull out the wrong plug and out comes flying a spring and check ball, through the air and across the garage never to be found again.

All 3 carbs needed attention, but the top two were starving the engine for gas, the middle carb was real bad. They said the residue was very typical of what the see in alot of carbureted marine engines running with ethanol now days.

Should see the boat back sometime in the next 3 days or so.