Tohatsu 3.5 Stalling

[Terrier]

In the process of breaking in my new 4 stroke 3.5 hp Tohatsu. Its now at about 4.5 hours into break-in. As I am cruising at around half throttle (or any speed for that matter) the engine will start to cut out (a couple of times or so) and then just stall. It then starts right back up on the 2nd or so pull. I take off and about 2 minutes later it does it again. I was able to go for about an hour (around the 3 to 4 hour during break-in) and it ran great for that hour. Note that the elevation is around 4700 feet.
Any ideas? Thanks.

P.S. Issue resolved. Engine runs great; see my later post dated 3/27/09

 

[steelespike]

Re: Tohatsu 3.5 Stalling

Is the tank vent open and clear?If its a remote tank does squeezing the primer bulb help?

 

[Mas]

Re: Tohatsu 3.5 Stalling

What does the "owner's Manual" say about operation at higher elevations?

MAS

 

[Terrier]

Re: Tohatsu 3.5 Stalling

Is the tank vent open and clear?If its a remote tank does squeezing the primer bulb help?

Integral tank, and yes the air vent is open. however, at one point I tried running with the vent closed and it seemed to not have an issue. Go figure?
Thanks for the input.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

What does the "owner's Manual" say about operation at higher elevations?

MAS

Nothing that I have found. I do have a somewhat similar problem with my 25 hp Johnson 2 stroke; however, it just reduces in rpm temporarily, but does not ever stall. I guess that is the proper word choice for the Tohatsu problem; it is more of a sudden reduction and then back to normal rpm and then reduction and then back to normal and then reduction and then stall. Thanks for your input.

 

[Mas]

Re: Tohatsu 3.5 Stalling

Being that it is a new motor, I would be hard pressed to say that anything is wrong with the motor...I'm still thinking carb however.

Did you replace the plugs after break in? Proper gap?

How new is the gas???

MAS

 

[TOHATSU GURU]

Re: Tohatsu 3.5 Stalling

Sounds like trash in the carb. Run it by a dealer and let them look at it.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

Being that it is a new motor, I would be hard pressed to say that anything is wrong with the motor...I'm still thinking carb however.

Did you replace the plugs after break in? Proper gap?

How new is the gas???

MAS

Still in brak-in mode.

Brand new 91 octane. I guess it could be a bad batch.

I'm going to try it again today and last night I put in a new plug, properly gapped although the original plug looked good and was properly gapped.
Thanks.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

Sounds like trash in the carb. Run it by a dealer and let them look at it.

Is there some type of fuel addditive that might help, or can I try to take carb apart myself?
By the way, I am going to try another batch of gas, in the unlikely event I had a bad batch. I'll be taking it out again soon and will report accordingly. Thank you.

 

[Mas]

Re: Tohatsu 3.5 Stalling

You're still in the break-in period...5 hours this season???? Or, has the motor been sitting the last couple of years and used intermittently?

MAS

 

[TOHATSU GURU]

Re: Tohatsu 3.5 Stalling

No additive will help and you should take it into a dealer as it is in warranty...Working on the engine yourself while it is in the warranty period is almost always a "Bad Idea". At worse, the dealer will charge you $100.00 to clean the carb....Now, if you really feel up to the challange of cleaning your own carb, go right ahead, but if you have never done one before, your own engine is a bad place to start learning.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

I took it out again today for another 4 hours. So now there is a total of about 8.5 hours on the brand new engine. Slow trolled most of the time today. I also did run it at 1/2 to 3/4 throttle and no problems. However, toward the end of a long 1/2 to 3/4 throttle run, it cut out and stallled about 3 different times about a minute apart. It may be noteworthy that it was very low on fuel when the cutting out occurred today. Didn't do it again after I filled up the tank. However, no real long run at 1/2 to 3/4 throttle.

I don't know if this is related but when slow trolling, it will stall if I run it with the throttle all the way to the start position; but when I take it out of gear, it will run at a pretty fast idle, especially after it is well warmed up.

Maybe I am too optimistic that it can be worked out or taken care of short of taking the carb in for cleaning. Thanks again all for your input.

 

[TOHATSU GURU]

Re: Tohatsu 3.5 Stalling

Have you tried adjusting the idle screw on the carburetor? The engine should be running around 1250 RPM at idle, not in gear. If it is running at less than that it would probably die when you drop it in gear....Also, the engine trim angle on your boat may be causing the engine to starve for fuel when the tank is close to dry. I've heard of two 3.5's in the last four years where people reported that the engine would not stay running when the tank was low. In both cases it was due to the angle of the engine...IE the part of the tank that has the fuel **** was higher than where the fuel was.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

I have adjusted the idle screw. It looks like it just regulates the throttle position and is not a needle type idle adjustment, right? The problem with adjusting the screw is that it seems like it already has somewhat of a slight clunk when I put it in gear and I am afraid that if I adjust the idle higher, it will clunk hard when going into gear. Unfortunately, I do not have a tach.

As to the trim of the engine, it looks like it could be trimmed in (lowest point) a little too much. It is on a scanoe, and I was remotely thinking that might be an issue. I bought the engine to also use as an auxilliary/trolling motor on a larger aluminum boat. I was going to try it on that boat but can't get it out of my yard yet due to leftover winter ice. Maybe next weekend.

Thanks again for your thoughts and advice.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

Pleased to announce that my 3.5 Tohatsu runs great. Took it out today on my 15 foot aluminum v hull instead of my scanoe. I ran for about 3 hours and it ran great and even trolled without stalling. No more problems whatsoever. I am so pleased with the 3.5. It pushed the 15 footer along into a decent headwind at a good and steady pace; perfect auxillary/trolling engine for that boat. Engine is now fully broken-in.
Must have been something to do with the scanoe and not the engine. Next time I take it out on the scanoe, I will try to adjust the trim different as what Tohatsu Guru referenced may have been the issue. Also, the engine is a long shaft and the scanoe transom is around 18" while the 15' aluminum has a 20" transom.
In any event, thank you all for your previous input.

 

[Terrier]

Re: Tohatsu 3.5 Stalling

UPDATE: After having used my Tohatsu on the aluminum boat a few times (running great), today I used it again on my scanoe. Moved the trim angle of the engine up one notch and it ran great. In any event, I am very pleased with my Tohatsu.