Tohatsu 3.5 two stroke won't tickover. Help please.

[npf1]

Tohatsu 3.5 two stroke won\'t tickover. Help please.

Just purchased a 2005 two stroke Tohastu but it dies at tickover and seems to miss occasionaly at lower revs. I've changed the fuel (50:1), plug and checked the carb bowl, but still have the same issue.

After running at tickover, the plug is wet with fuel. Removing the idle screw seems let the engine tickoover (bit high) without missing. It would appear that it might be getting too much fuel, but I'm getting a bit beyond my knowledge here.

Anyone any thoughts on what it might be? Is it possible to adjust the jet, if so how?

Thanks in advance.

 

[misterg]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

I suspect the float valve isn't seating properly - does it drip fuel from the carb if you leave the fuel on when it's stopped? Most probably a piece of rubbish has got into the top of the valve, but can't get through. Depending on how the carb has been put together (not sure about this engine specifically) you can either remove the valve from inside the float chamber, or as part of the fuel connection barb from the outside of the carb to get to the float valve to clean it out.

Take careful note as to how the float arm and needle fit together - sometimes the float arm hooks onto the needle, and sometimes it bears on the end. I suppose the same thing could happen if the float, or its linkage was jammed.

edit to add: Check that airway to idle screw is clear (remove screw & blow down the hole with a bike pump, etc.)

0.02p

Andy

 

[JimMcMillan]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

You dont say which model but i assume it is low hp. At the top of the carb is the t/o jet, normally a small steel screw with a spring over the shaft of the screw, sounds like it maybe running too rich so tighten screw slowly till engine runs smoothly.If that dont work try unscrewing. If that dont work then remove carb and clean all jets.and reset tickover jet as above.

 

[npf1]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

It's a 3.5hp two stroke.

 

[BobnLesley]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

...the fuel (50:1)...

I doubt that it's critical (I run mine at about 75:1) but the recommended fuel/oil ratio on the 3.3 is actually 100:1

 

[npf1]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

it's says 50:1 in the manual.

Thanks for all the replies. I'll try meddling with the carb as described above.

 

[seumask]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

Strip and clean the carb, including dismanteling the float bowl, where you need to beaware of the float valve when you take the float off. i.e. do it over a bowl to catch any bits. It should be a less tha 20 minute job.

 

[Rob_Webb]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

When you say "just purchased" do you mean new? If so, just go back to the dealer?

If not, then maybe still take to a servicing agent if you run out of steam with these ideas?

 

[matelot]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

If your plug is wet it suggests over rich mixture at idle and this will be controlled by an idle jet - usually a tapered needle with a spring round it. So as others have suggested, check the idle jet and also check the fuel bowl to ensure that the fuel needle is shutting off. Quick way to do this is to remove the carb, turn it upside down and try to blow down the fuel inlet spigot. It should not be possible but thwhen you turn the carb right way up, it should then be possible.

Are you sure you have the correct grade of spark plug. If the plug is too "cold" (ie the electrode is too shielded) then it will oil up, look as if its soaked in petrol, and can refuse to idle.

The other "odd" thing that can stop your engine idling is load on the prop. I had a Mariner once (same maker as your engine I think) and it had the quirk that as the alloy in the leg corroded, it squeezed the stainless bowl that the water pump ran in, which then became difficult to turn and prevented the engine from idling. If this is the case, then your engine will be hard to turn over on the pull cord.

 

[Cantata]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

[ QUOTE ]
When you say "just purchased" do you mean new? If so, just go back to the dealer?

If not, then maybe still take to a servicing agent if you run out of steam with these ideas?

[/ QUOTE ]
...and if it's new it should be run in on a 25:1 mix, by the way.

 

[npf1]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

It's a 2006 engine. The new plug I put in is same number as shown in the manual.

I'll strip the carb in a couple of weeks when next down at the boat. I'll post the results on this thread, if anyone is interested. Thanks

 

[npf1]

Re: Tohatsu 3.5 two stroke won\'t tickover. Help please.

I've now dismantled and cleaned the card per the above but won't have a chance to run/use the engine until the weekend.

I did notice that the needle has a sort of paint on its pointy end - is this normal?

Thanks in advance.