2003 Tohatsu Idle Problem?

[Johnshan1]

Hell everyone, I bought a 2003 Tohatsu 40 hp 2 stroke a couple months ago, I have put 46 hours on it now and love it, except for the idle.<br /><br />When I troll with it at 750 rpms it will suddely run rougher and make more noise, then suddenly go back to running smooth again.<br /><br />This occurs randomly with no rhyme or reason. Sometimes it doesnt do this, other times it happens so much you cant get rid of it.<br /><br />It sounds like its mis-firing but if its making the noise and you punch the throttle up it is smooth and doesnt stumble, and the roughness/noise has stopped. If you drop the throttle to idle again it does it again off and on.<br /><br />Any ideas at all? is this normal? I am using Tohatsu regular oil, no pre mix!<br /><br />If I rev it up when its "acting" up theres no cloud of smoke or anything so I dont think the motor is flooding or loading up with excess oil or anything.<br /><br />Thanks everyone let the ideas roll!

 

[Johnshan1]

Re: 2003 Tohatsu Idle Problem?

I should mention the RPMs stay the same the whole time it "acts up". If I bring the idle up to 1000 rpms it still does it as well.<br /><br />-John

 

[james082273]

Re: 2003 Tohatsu Idle Problem?

John,<br />I bought a 2004 40hp Tohatsu last December and it does the same thing. I have pretty much decided it has more to do with the gear case than the engine. Mine won't hardly do it if your trolling against the wind, keeping pressure on the prop. But going with the wind, riding the waves makes it worse. I'm hoping after a little more break in time it will get better but I'm not so sure. I've tried different plugs, oil, props, gas, and even idle mixture with no success.<br /><br />I am glad to see someone else complain of the same problem as it confirms the mechanics diagnosis of normal. At least that's what I was told. Have you talked with any mechanics about it?<br /><br />It is annoying since I troll very often but it is livable I guess. I am happy with the motor other than that problem but if I had to do it again, aware of this issue, I would have never bought the Tohatsu. <br /><br />Let me know if you find a solution I would GREATLY appreciate it.<br /><br />James

 

[Johnshan1]

Re: 2003 Tohatsu Idle Problem?

Thank you for your reply! At first I was wondering if it was comming out of gear, but thats not the problem. <br /><br />Like you said I bet we just have to live with it, but I have not asked my dealer about it yet, I will though. I am also going to switch to Amsoil and see if that makes a difference.<br /><br />I keep telling myself I should have bought the Tohatsu 30 4 stroke, at the time when I bought the 2 stroke we never did any trolling, now its all we do. <br /><br />Like you said its something we can live with I suppose, and man that motor has some power thats for sure, great on gas too.<br /><br />I will keep you updated as to what I find out, take care.<br /><br />-John

 

[lewkster]

Re: 2003 Tohatsu Idle Problem?

I have the 2002 40 2 stroker also. I thought it idled ok. Not the same as a 4 stroke, ( a friend bought the 30 4 stroke nissan). The 30 was quieter and smoother, but thats a 4 stroke. I actually only use my 40 for trolling in higher winds as my boat is light for the 40. I bought a used 2 horse evenrude for my troller. But over all am pleased with the motor, seems tough and a very quick running motor. I'm not a mechanic of any sorts but wonder 2 things from your post. Are your carbs synch correctly and is the timing set a bit forward for the idle position. Maybe contacting the dealer to have them checked, specially if still under warranty. Also I guessed from initial quickness of motor that flywheel was perhaps alittle light. a light flywheel maybe adding to idle not being as smooth. Trade offs to a heavier motor. just a guess? Great on gas and fast like stated above me. Not to mention power trim is a back saver and makes boat control better, all for 3 grand. I would not have spent more onna motor and from other posts sounds like a tough engine. I am happy with it.

 

[Johnshan1]

Re: 2003 Tohatsu Idle Problem?

Thanks for the comments, perhaps I am just being a little to picky about the idle, more or less just curious if mine was an isolated case. <br /><br />I know its one heck of an engine, lots and lots of power ready whenever you want. Sure is nice to go from 3/4 to full throttle and feel it pull even more <br /><br />Do you guys notice the paint is a little weak on these engines? Seems like a little bit of a touch and shes losing paint down to primer..

 

[DJ]

Re: 2003 Tohatsu Idle Problem?

Just throwing out some ideas here.<br /><br />Can you guys see anything happening if you idle with the cover off?<br /><br />If the advance mechanism were to shake down to a certain point, it may effect timing. Opening the throttle would bring it back to normal.<br />If you idle the engine with the cover off, try (CAREFULLY) moving the throttle linkage under the hood. Any play there?<br /><br />Also, possibly, the idle stop is set too low?

 

[james082273]

Re: 2003 Tohatsu Idle Problem?

I have tried running with the cover off and everything looks fine. The linkages are all nice and tight. Raising the idle speed will help but not eliminate it.<br /><br />What seems to be happening (to mine at least) is very difficult to explain. Think about this..with the motor sitting in the drive way and putting it in gear you can grab the prop and turn it back and forth maybe a 1/4 to 1/3 turn. This is just the way the clutch assembly is built. Pretty much all outboards are this way I think. What my Tohatsu is doing when the noise starts (I think)is the prop is bouncing back and forth that 1/4 to 1/3 turn. Does that make sense? Almost like a chatter that two gears would make if there is to much lash. Well you say that wouldn't make much noise would it? It does suprisingly enough. If I turn and go against the wind which keeps pressure on the prop it stops. Or give it more gas even and it will stop.<br /><br />The idle quality out of gear or in gear on the trailer (pressure on the prop) is as good or better than any outboard I have ever owned. I e-mail Tohatsu USA this weekend and I'm waiting on a reply.<br /><br />Yes the paint is pretty weak. I put a few scratches in mine just bolting it to the boat. Also not sure of your boat but mine is an open 1553 jon that weighs about 400lbs empty. My engine came with a 12 pitch and I have tried a 13 and a 14. It will turn the 14 but you loose a bunch of response and I don't think it is much faster. The 13 is probably the best all around. But I'm sticking with the 12 because it is always so windy/rough in Texas you can't go that fast in a jon anyway. <br /><br />Thanks for everyones help!

 

[Salmon Tub]

Re: 2003 Tohatsu Idle Problem?

I had that with my '96 40. It started after I leaned out the carbs a bit. I had the motor on a 17' Whaler and out in the ocean, when heading with the swell, that "noise" would occur. I could not get any of the local service dealers to confirm this unless I paid them $75 and hour to go fishing with me. I came to the following conclussion: When going with the swell, the effect of the wave is more pronounced because the duration of it's effect on the boat is longer. As the swell approached the transom, it caused the boat to "surf", relieving some, if not all of the load from the prop. This created a lean condition. At troll speed, a lean condition will not cause damage to the engine such as it would at high speeds in the case of a plugged or undersized jet. The worst case scinario would be that the engine would die, and then you would need to start it back up. At first I thought it was due to a rich condition, causeing the engine to load up, but I have found that that was not the case. I repowered to a 90 hp Nissan a few years ago and ran into the same problem. With the stock 17" pitch prop, I was able to get rid of the problem by richening up the pilot screws, but, the motor kicked alot with that setting. I then went to a smaller prop and solved the problem. The 40 hp had a 13" pitch prop. I have found that a 2-stroke will load up any time it is run for long periods of time at low rpm, even with an oil injection system. You need to run it closer to WOT (4000+) for 5-10 minutes in order to "un-load" it. After you troll for a while, never accelerate fast, but rather gently bring it up to speed, it may feel like it is missing a little, throttle down a bit until you feel her smooth out and pick up speed on it's own. I have found that the settings in the service manuals do not account for the new oxygenated fuels so though your setting may be per book specs, oxyginated fuel create a bit of a lean condition by their very nature so you may need to compensate a little. Make sure that the carbs are in sync. It is difficult to sync. the pilot screws according to the book procedure with just the standard RPM guage but it is possible. Good luck.

 

[lewkster]

Re: 2003 Tohatsu Idle Problem?

I am not noticing this condition with my 40 nissan to the exstent you guys are saying, which brings to mind fuel types brought up. I run 91 grade with a bit of seafoam, seafoam to help keep engine clean and 91 grade as I believe it is free of the alcohols.

 

[TOHATSU GURU]

Re: 2003 Tohatsu Idle Problem?

Well, at 750 RPM the engine is probably starving for fuel. I would think that one of three carbs is running a little lean and that the idle is borderline. All three carbs need to have the airmixture adj checked, than set the idle speed at 800 in gear, at idle.

 

[Johnshan1]

Re: 2003 Tohatsu Idle Problem?

Just wanted to give a little update, I have not touched the motor all summer, and its got a touch over 70 hours on it now, I dont have the noise anymore, maybe I dont notice it but ive been listening and I no longer hear it, if I do its much much quieter than before. Maybe its in my head? Just a little update. <br /><br />Also my owners manual states 650-700 rpms for idle speed while in gear. <br /><br />-John

 

[TOHATSU GURU]

Re: 2003 Tohatsu Idle Problem?

I hate it when I'm wrong. I was off by 100 RPM's and your manual is correct.

 

[Johnshan1]

Re: 2003 Tohatsu Idle Problem?

I wasnt trying to make a big deal out of it at all sorry if I came across that way, I really appriciate your input on this subject as you obviously have more time with these motors then problably all of us combined, I was just reading the manual and figured I would throw it out there, thanks for your help!<br /><br />-John

 

[TOHATSU GURU]

Re: 2003 Tohatsu Idle Problem?

I was really laughing at myself for giving you the wrong values. I had not yet received my caffeine fix when I responded earlier with the wrong RPM range. After awhile all brands and models start to merge into one and the potential for my screwing up increases.