fast idle

[robman66]

Took the boat out on the water for the first time today. Started right up, no problem. Idled around 1100-1300rpm, sounded great. After cruising for a minute, and then putting the throttle handle in idle position, the motor stayed around 3000rpm. I bumped the throttle up a bit, and then brought it back down, and it was idling around 2800rpm.
Bringing it into the marina was tricking due to the high idle. I would have to go from neutral to reverse just to slow it down in the channel. But every time I switch it from N to R it would bump the rpms up to about 4000, and then it would drop to about 3000. It made docking it quite scary.
What could be causing the high idle?
Hoping to go out again tomorrow, but only if I can find a solution to this first. Thanks.

 

[Dr Honda]

On the EFI merc engines... there isn't a "High Idle" system like in some engines.


SO... either your throttle link/cable is sticking.

OR... the rod that controls the ignition timing is stuck.

OR.... the throttle body is VERY dirty.


OR......... The small cable, that adds some throttle, when you turn your steering all the way to one side, is stuck. (I disconnected mine)

 

[robman66]

Thanks Tony. I lubed up the throttle cable really well, and it moves smoothly, so I don't think it is sticking.
I will check the ignition timing rod. Is this located close the rod that I disconnected when I removed the oil injection system?

And I will disconnect the cable that adds the throttle when steering fully. Should I disconnect down at the motor, or in the helm?
Actually, come to think of it....I was looking at that cable in the helm and couldn't quite understand how it worked, as when I turned the wheel all the way, it didn't seem to pull the cable at all. I wonder if it is already being pulled down at the motor?
I will check that right away.

And would suggest Seafoam, to help clean out everything? I have heard good things and bad things.

Thanks again.
Rob

 

[robman66]

ok...it seemed that there was a linkage, from the throttle arm to a cam that pushes a roller that I'm guessing was for the oil injection (no longer needed)? It is the same roller system that the throttle assist (while steering full) connected to. I disconnected the bent arm that linked the cam to the throttle arm (it was sticking, and wasn't snapping back to idle), and I pushed it to idel. I also disconnected the throttle assist cable that was under the helm. Heading back out on the water again. I'll let you know how it goes.
Thanks again Tony.

 

[robman66]

OK, don't do what I did above. Boat idled great, but no throttle at all.
So now, I put it all back together, making sure everything is lubed up well....and now when I start it, it races at 5000 rpm. I still have throttle control, which increases rpm even more...but only idles at 5000rpm. I took a couple pictures of it re-assembled, can you please tell me if I have something installed wrong. Everything seems to be back to its idle position, but obviously something isn't.
Any help would be greatly appreciated.
Thanks

 

[robman66]

Here is another picture, with some explanations.

 

[Dr Honda]

The thin cable is the throttle add'er. The top will pop off, and the cable will come out. (not needed)


The cam and the roller look right.


If you look at the links on the side of the throttle body... make sure the butterflies are closing.

 

[robman66]

Tony,
I'm feeling dumb again, but can you direct me where to find the throttle body, and the aforementioned links? I've looked all over.
Do I need to removed something?

 

[robman66]

Ok Tony, I found the throttle body housing, on the microfiche picture I have attached. Are you saying I will be able to tell if the butterflies are closing by the position of the lever (#8 on the diagram)?
It does stick a bit, and does not return to idle on its own everytime. (almost like the spring isn't strong enough).
I have manually pushed that back to idle position and it still races to 5000rpm when I start it.
I'm praying that I don't have to remove the entire cover and get to the butterflies themselves.
I can do that over the winter, but sure don't want to do that with a little bit of summer left.
Please tell me there is an easier way....lol.

Thanks
Rob

 

[Dr Honda]

I read your first post... and started looking for a picture. I'm glad on the second post, you linked the pic.


Yes... that is the throttle body. The butterflies inside are what physically control the air into the engine.

If there is some sticking linkage in there... it needs cleaned, and lubed. If the valves are dirty... and that's causing it to stick... then there isn't going to be an easy way to clean them. If you try to use a spray cleaner of some kind... you will wind up pushing dirt into the engine. On this engine... there basically isn't any kind of air filter.


If you can see that the links, going into the butterfly shafts are sticking... I personally wouldn't keep running the boat. It could be very dangerous. Also... trying to lower the reverse gate with 5000 RPM of thrust... it could break the bucket, and that would leave you in a bad position.

 

[robman66]

Okay, I will take a look at the linkages connected to the butterfly shafts when I get home tonight.
Hopefully it is something external that I can clean up.
I have not been running it. Started on the hose in the driveway for a second, to see if it was still racing. It literally ran for 3 seconds.
Putting it in the water like this would be quite risky...lol.
I'll let you know what I find tonight.
Thanks again.

 

[Dr Honda]

Wellllllll.........................



I do have another thought... Look for an air leak.

There are a bunch of small hoses around the intake. Most of them are to scavenge oil from the internal corners. If one (or more) of those hoses are broken, or came off the fitting... then they will draw air. You can see them below. (I changed mine, and they are now yellow) They are hooked to both sides.

 

[robman66]

Thanks Tony. I will check them tonight.

 

[robman66]

Tony, from what I can see from the picture of your engine is that there is a bank of 3 pairs of butterflies. I'm guessing there is a common shaft for each of the pairs? Will this shaft be visible from the outside of the throttle body? Will the shaft be visible on both the port and starboard side? Do I need to remove the started to access from the starboard side? What about the port side, do I need to remove anything to get to the shafts? Thanks

 

[Dr Honda]

Actually... there is only 2 sets of butterflies. But there are 3 openings into the engine, where the fuel injectors sit. (I wish I would have taken a couple pics of my fuel unit)


Basically... the butterflies sit in between the 3 rectangle openings you see on my engine. So... the air comes in between the manifold... past the butterflies. Then, is drawn though the plenum of the ail handler.... past the fuel injectors, and into the reed openings of the engine.


The 2 shafts do come out on either side. On the starboard side... The lower shaft is what the TPS is connected to. the upper shaft just pokes out.


On the port side... the shafts are connected to all the goofy linkage. The bottom one has the link for the oil pump.




OK... sitting here, and thinking..... check these too

1) Did you remove the oil system? If so... did you disconnect the link rod from the throttle body? If not... it's flopping around, and can be making it bind.

2) Where you the guy asking about the TPS and you couldn't remove it? If you were... maybe something is binding in that. (it should just lift out with the 2 screws removed)

3) Look for any loose bolts on the back cover (plenum cover) of the throttle body. If that cover isn't sealed... it will suck air, and rev up.

 

[robman66]

I have attached another picture, showing the throttle body (I believe).
Is it a single butterfly plate at the top? If so, what do I have to remove from the engine to access this.
I've done the oil bypass, so the oil bottle and components are already gone. According to this isometric diagram, it doesn't look like the flywheel needs to come off.
I'm going to pick up a can of carb cleaner and clean up the linkage, spring, etc. Hopefully I can get inside the throttle body and get it cleaned out as well. The boat sat for an entire year, so I'm guessing it is just gummed up a bit.

 

[robman66]

Also, that isometric diagram is of a 2002. Mine is a 2000. Other than the alternator setup, not sure if much is different.

 

[robman66]

Sorry Tony, I should have read your reply before posting my last 2 comments.
Ok, so now that I understand there are 2 sets of butterflies, I should be able to track down the shaft they pivot on.
I did remove the oil system, and yes, I did remove that link with the ball joints, as I didn't want it getting jammed in there.
I am not the guy that was asking about the TPS. From what I've seen that thing costs, I'm praying that isn't my problem.
I will check for any loose bolts on the cover as well.
On the starboard side, am I going to have any adjustment issues if I remove the TPS to access the shaft, or will it be all set when I re-install it?

 

[Dr Honda]

There was a major change after the 2001-1/2 engines. As you figured out... you have the earlier engine. Other than the "Core" of the engine... the are a totally different beast.

1) New fuel injection, and intake
2) New alternator. (belt driven)
3) Electric oil pump
4) New computer. (fully smartcraft compliant)
5) new ignition

 

[Dr Honda]

....
On the starboard side, am I going to have any adjustment issues if I remove the TPS to access the shaft, or will it be all set when I re-install it?

Assuming it's right now.... you can mark it, and just put it back on. But personally.... I would verify it's position after putting it back.

Regardless... the TPS won't cause the high idle. (unless it's holding the butterfly's open)

 

[robman66]

okay. I have a lot of things to check tonight. I'll let you know what I find.
Thanks

 

[robman66]

I removed the fuel filter mount to get a better look at the butterfly plate shaft. It was dirty and gummed up a bit. I sprayed and cleaned with carb cleaner. Nice and shiny again. I marked the TPS, and removed the 2 screws and mounting plates. But I couldn't get the TPS off. I even tried to pry it a bit, but knowing that it is worth its weight in gold, I wasn't going to risk breaking it. Especially not with only a few weeks left of the boating season.
On the port side, I loosened the vapor separator and pulled it out of the way, only to find the other linkage that I didn't know existed before yesterday. I thoroughly cleaned the lower linkage system (arms, pivots, spring, etc.), as it was really gummed up. I did the same for the lower linkage. Everything now moves nice and smoothly, with no sticking lever arms anywhere. It seemed that both butterfly plates were returning to their closed positions. I would advise everyone to not use white lithium grease on these parts. It seems to cause more harm than good.
I didn't have a chance to pull the boat out of the garage and hook up the hose to try it last night, and I can't guarantee I will have a chance tonight, but tomorrow for sure.
I did check the small hoses that run from side to side, and everything seems to be connected and in good shape, so I'm hoping there are no leaks.
I'm confident the cleaning of the linkages and the shaft ends are going to solve my issue. Fingers are crossed.
I did pick up a can of Seafoam as well. I don't think it is going to cause any harm by giving the inside of the engine a good cleaning as well.
I'll let you know how I make out as soon as I get a chance to pull it out of the garage.
Thanks

 

[Dr Honda]

Yep... I agree. that spray on "White grease" can cause all kinds of issues. Basically... it can either get hard... or it will pic up dirt, and eventually bind up. Personally, on stuff like this... dry and clean is better. I guess the only lube on mine in storage oil from my last witerazation.


As far as seafoam..... I don't like it. It's a solvent, and basically counteracts the small amount of oil that we mix with the fuel. (regardless of premix or injector) I know Merc specs out a few cleaners.... but I haven't dug into them yet. Personally... if I was going to "De-carbon" my Merc.... I would get a small 3~5 gallon boat fuel tank, and run it on that for the cleaning. (using the Merc brand additive) But to dump it into a +40 gallon tank is just too much run time.

 

[robman66]

Note taken. I have not put into the gas tank yet. Good chance I won't now.
I'm just hoping my cleaning of the linkages has solved my problem.
Thank you for all of your help Tony.

 

[robman66]

okay, solved my fast idle problem. It was much simpler than I thought. When I had taken everything apart the first time, cleaned and lubed everything up, and thought I put it back together properly, I hadn't. The cam was correct, the roller position was correct, but I had moved the screw in the silver linkage, and what I thought was the original position wasn't.
It was holding the butterfly plate open and causing it to idle at almost 5000 rpm. I disassembled again, loosened that screw, made sure the throttle body was closed, the roller was on the cam, and then I tightened the screw. I re-assembled everything, fired it up, and it purred like a kitten. Finally. Something so stupid. I knew I must have done something, as it idled perfectly before disassembled it.
I have attached a picture of the linkage and the screw that I had adjusted wrong.
I have also attached a picture, asking what the other linkage arm does, and what the adjustment screws do, and what their affect is on the engine. I'm hoping someone can answer that.
Thanks Tony, and everyone for your help.