'89 Yamaha Excel V6 225 - High Idle. Clunking noise when in gear.

[Gary4000]

Hi all, Having another problem with this outboard. I had a dead computer previously, and a replacement resolved my starting issues.
However now I am having extremely high idle (Anywhere from 1600-3000RPM) and a clunky/clicking sound coming from the lower unit when shifting into forward or reverse.

The RPM climbs when I give it throttle in neutral, but doesn't fall back down at idle unless I choke it.

I only shifted into gear once at 1600, and shifted back immediately once i heard that clunking. With the choke on that kept the RPM around 500 where I felt better about shifting but still heard the same clunking noise. Not just one when shifting but continuously. I'm avoiding putting it into gear, i'm pretty sure that noise means something is going to get destroyed very quickly like that.

I noticed a loud hissing, like sucking through a straw, more noticible with choke. It seems to be coming from the Carb. Could this have anything to do with high idle?

I do have a Yamaha service manual. But i'm not sure where I should start looking.

Thank you for reading and I appreciate any help.

[pstephens46]

Sounds like it is sucking air and running lean. You will cook a piston so I wouldn't run it like that. Don't shift at high rpm either. Not good for the gears.

I might run it briefly at idle to find that leak...

[Gary4000]

Sounds like it is sucking air and running lean. You will cook a piston so I wouldn't run it like that. Don't shift at high rpm either. Not good for the gears.

I might run it briefly at idle to find that leak...

Could I use the cigar method for finding a leak? Where would be a good place to blow the smoke in?

Smoky as hell when i first started it. Smoked out the entire yard. Calmed down after about 30 sec of running. I had to keep choking it to keep the RPM below 1000 but its hanging around 1200. 500-600 choked. I didn't leave it running more than 2-3 minutes and most of it I had to keep the choke on to avoid RPM >1000

I noticed the fuel had a greenish tint to it. Googled it and it seems normal, I do have Rec-90 fuel but it is a couple months old. Drain it?

I did notice this arm doesn't sit back all the way.
Throttle.jpg
I don't know if it's for throttle or idle control, I think throttle? But I didn't see any reference to it scanning through the service manual. I can push it back by hand and that keeps the RPM down in the 1200 range.

[pstephens46]

Cigar, ear may work. Hoping some of the 2 stroke guys will weigh in here.

How handy are you?

[Gary4000]

Cigar, ear may work. Hoping some of the 2 stroke guys will weigh in here.

How handy are you?

Not sure where to blow the smoke in, The carbs? Lines from the carb were zip tied down by the previous owner, should probably do something about that...

I have some experience in doing minor repair jobs on my truck, next to none on an outboard.

[pstephens46]

Can you identify where the hissing sound is coming from?

Not sure what lines you are referring to.

Pics and videos help. Do you notice hissing at idle?

You may have to find a mechanic

[panasonic]

Could I use the cigar method for finding a leak? Where would be a good place to blow the smoke in?

Smoky as hell when i first started it. Smoked out the entire yard. Calmed down after about 30 sec of running. I had to keep choking it to keep the RPM below 1000 but its hanging around 1200. 500-600 choked. I didn't leave it running more than 2-3 minutes and most of it I had to keep the choke on to avoid RPM >1000

I noticed the fuel had a greenish tint to it. Googled it and it seems normal, I do have Rec-90 fuel but it is a couple months old. Drain it?

I did notice this arm doesn't sit back all the way.
[ATTACH]3275[/ATTACH]
I don't know if it's for throttle or idle control, I think throttle? But I didn't see any reference to it scanning through the service manual. I can push it back by hand and that keeps the RPM down in the 1200 range.

That would be your throttle control arm. Disconnect that arm at the bottom where the throttle cable hooks up to it. Check that once it is disconnected that it moves back and forth smoothly and goes all the way back to idle stop.

There should be another linkage that goes to your timing plate under the flywheel. This should move freely as well.

Start the engine and see if it idles with the throttle disconnected as noted above. If it does then you have a sticking throttle cable. If not try pushing the throttle linkage on the engine back by hand and see what, if anything is sticking there.

Your timing plate may be sticking and causing the engine to not return to idle.

Could you take another picture of the same area with the carbs included?

[99yam40]

yep timing being too far advanced at Idle will cause a high idle, even if the throttle plates close as they should

[throrope]

"The RPM climbs when I give it throttle in neutral, but doesn't fall back down at idle unless I choke it."

This appears to be a new to you outboard that endured fiddling from the prior owner. Adjustments are available to refine operation back to manufacturer's specs, not overcome problems and twisting knobs to get desired results is a tattle tale of issues requiring correction. Fortunately, you have a traditional two-strokes with history of great reliability and ease of maintenance and sound like someone familiar with tools.

I suggest sequentially visually tracing the fuel system with the service manual (not owner's) to insure all is as built by Yamaha and return any encountered changes to factory original. Then sequentially adjust all linkages, ports, etc. strictly by the manual. I recall on our 90 Hp TLR near all adjustments are manual with hand tools against block marks. If performance doesn't meet specs, address issues.

One easy place to check for intake leak is the "O" ring between the carb and intake. Due to possible prior owner fiddling, it may be damaged or not there.

When resolving crapped up carbs left to us by the prior owner, we made the mistake of not addressing the upstream tank and fuel hoses and found ourselves exactly where we started with the next key turn due to ethanol related degradation. Replacing everything upstream of the outboard was cheaper than a failed trip. Plenty of threads are available on methods used to avoid fuel issues.

When I realized our aged and sticking control cables were making life difficult, I was pleasantly surprised it only took $50 and 20 minutes to replace them. Yes, when we had high idle rpm issues, it would clunk into gear.

If you don't know how old your water pump impeller is, I suggest a change-out to avoid an on water issue. This will also enable you to plan the next renewal rather than finding out you should have done it the hard way. Same with the lower unit oil change if only to check for water contamination. These items are dirt cheap compared to the damage caused by failure.

Hope this helps, good luck and please keep us posted.

[Gary4000]

Just wanted to thank everybody for their advice and the information. I'll be going over it more in depth throughout and work on it during week after work.

I do agree this outboard was bandaid fixed plenty by previous owners throughout its lifetime. Zip ties, Unknown cut wires, clogged zerk fittings and electrical tape all over. I almost regret buying it and wish I was more mechanically inclined at the time to see all the red flags, but hey gotta live with my decision, Would be a good learning experience as well when I manage to get this thing running.


Will follow up later.

[Gary4000]

Well I found at least one future problem, Plastic oil linkage was split and pretty much fell off the rod. Covered in grease(?) or oil. Good thing its a small cheap part.

Took a few pictures. Not sure where the throttle plate is, Directly under the flywheel? Time to pick up a 30mm socket and strap wrench?

Sorry about the hyperlinks, Wouldn't post photos directly, Probably too big.

Carbs minus cover, Gaskets are in cover.

Throttle and Shift linkages? Long one looks like the shift linkage


Throttle control arm and cam. That arrow probably should be on the linkage behind it at closed, right? Also is that crack along the valve cover(?) to the left of it a concern?

Busted socket end hanging limply after moving the linkage by hand a couple times. Glad I found that now rather than later. Didn't touch the nut.

[99yam40]

throttle plates are in the carb, they are what the throttle linkage hooks to, to control the RPM