Tohatsu 2.5 Wont idle and Hard to Start

[Ns2.5a]

My 1996 2.5hp 2-stroke was sitting for a while and when i got it out I discovered that it had sheared the flywheel key, so i got one from another motor and stuck it in there and fired it up, but now to start it it takes 2-3 pulls with choke(to prime it), and then 3-4 quick pulls with full throttle and no choke, and then,it runs great above 1/3 throttle but i cant let it go below 1/3 throttle or it will die. I have taken the carb off about 6 times to check for any gunk inside, and its perfectly clean now. I have moved the clip on the needle to all four positions and it doesnt help. It has great spark (jumps 1/2" on spark tester) And the compression is about 80psi, but for some reason its running too lean or too rich, and the carb doesnt have any fuel/air screws, just an idle screw. I am just stumped on this one, if you guys could offer any help i would be greatly appreciative.

 

[pvanv]

Re: Tohatsu 2.5 Wont idle and Hard to Start

It's unusual to shear the magneto key on one of these unless you struck the bottom, and had a hardened shear pin installed at the prop (and even at that, probably would have destroyed the prop), or somehow had a really wicked backfire -- maybe a super-lean POP.

Normally, poor idle and low-speed operation is due to carb problems. Changing the clip location on the sliding jet needle won't address that, as that's for the main circuit. You may have a partially-clogged low-speed circuit in the carb. The sliding port carbs on these are pretty reliable, and fairly straightforward to disassemble and clean, but if it sat with fuel in it, I would see about disassembling it and doing a proper soaking in carb dip. If you just sprayed it out with spray-type carb cleaner, there is likely some stubborn gunk remaining hidden away in the low-speed emulsion section. A new carb is available 3D5031005M CARBURETOR ASSY. 2.5A2 $63.97, as is a repair kit 309871220M CARBURETOR REPAIR KIT 2.5A/3.5A $25.98, which is good if the needle/seat/float adjustment is problematic, but try a THOROUGH cleaning first.

 

[Sea Rider]

Re: Tohatsu 2.5 Wont idle and Hard to Start

If engine is same as the 2T/3.5 model, remove fuel **** from lower tank and check internal linear gas screen/filter (looks as a large worm) probably gunk/debris obstructed too, clean interior gas tank well clean/replace fuel ****.

Happy Boating

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Well $63 is more than i paid for the motor so thats really a last resort and i have checked the float needle seat by holding the float up and blowing through a hose into the fuel inlet and i couldnt blow through when it was closed so that seems ok and I have run it on a seperate gas tank and it runs the same so i dont think the fuel filter is the problem either , also the carb doesnt have a seperate idle jet, just the main jet, and two holes which i think are supposed to connect? maybe you guys would know.. so heres some pics of carb The first is the float level which i believe is supposed to be 2.3mm above the gasket, and it does look about right the second is the bottom of the carb with bowl removed (the main jet isnt blocked, its just the angle) and the red arrow shows the left passage which goes up the side and comes out by the choke (3rd pic) and the right passage (blue) just goes up the side and looks like it should connect to the left (red) at the green dot (4th pic) but it doesn't could this maybe be because this carb also fits the 3.5 and that is opened on that engine for more airflow? What do you think?

 

[Sea Rider]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Tohatsu 2T/ 3.5 carb definitely has wider gas passages than of the 2.5 model. One issue for sure, that carb really looks heavyly rusty, imagine it's inside gas passages. Give it a one complete day soak with proper carb cleaner.

Happy Boating

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Not to exclude your idea, as it is a good one, but this carb only has 4 holes that could be plugged, and i have cleaned all of them out with carb cleaner (spray can) and checked them with wire and a flashlight.. (the reason it looks so rusty is becasue it has been under water) and I dont have much money, as im only 15 and dunk style carb cleaner is $20 for a gallon.. (smallest size availiable here) are there any other possibilities besides the carb? or an alternative way to completely clean the carb such as boiling or something?

EDIT: I just saw that lacquer thinner works as an effective carb cleaner, i am going to soak it in some for tonight and will post results tomorrow after school.

 

[Sea Rider]

Re: Tohatsu 2.5 Wont idle and Hard to Start

I just saw that lacquer thinner works as an effective carb cleaner, i am going to soak it in some for tonight and will post results tomorrow after school.

Try acrylic thinner, gives me excellent results as we don't have more specialized carb cleaning solvents down here, remove all plastic, rubber parts and soak a full day and see what happens. Good luck and let us know end results.

Happy Boating

 

[TOHATSU GURU]

Re: Tohatsu 2.5 Wont idle and Hard to Start

"I have run it on a seperate gas tank and it runs the same"

You know that engine does not have a fuel pump so it can't pull fuel to the engine by anything other than gravity....Or magic

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Well more of a gas tube.. lol I sucked up gas into a tube and after draining the bowl I connected that to the carb. No magic here

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Ok, so after the carb clean I cleaned the gas tank and the filter (was hardly dirty) and put fresh gas in, and it still runs and starts the same.. the only thing i can think of would be an air leak in the casing. How would i go about checking for that?

 

[TOHATSU GURU]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Spray either around the case while the engine is running....That's not going to be the problem though. In the end it's still going to be the carburetor or ignition system.

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Well my engine was under water before i bought it and it still runs loudly like there is too much friction somewhere if that tells you anything... and I think the impeller is bad as well because it gets very hot, the tell tale is showing water flow, but it doesn't come out forcefully. (its a solid stream for about 3" and then it breaks up) I just don't know what it is at this point because it has great spark and i believe the carb is clean . I really wish the carb had adjustments though..

EDIT: After reading tohastsu guru's post on the cruisersforum about the 2.5 and 3.5 bieng the same i was wondering if I could just buy a 3.5 carb and throw it on here to solve my problems and get a hp boost, would this work? I also read about a restrictor plate behind the carb, is it possible to remove that and increase hp?

 

[TOHATSU GURU]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Sunk? This might be as simple as corrosion on the bearings causing too much friction for low speed operation. Depending on the exact model number of your engine, you may be able to boost hp. You would need to look at the parts books available at www.internetoutboards.com and see what the difference is between your 2.5 and what the 3.5 was in that series.

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

I bought it after it sat in a warehouse during katrina. I had thought of the bearing friction, but when i had the cases apart the bearings were moving freely(i could flick my finger and spin them 3-4 revolutions) albeit a bit roughly and as they were pressed on to the crankshaft i opted not to replace them.. i wonder if it will come back to haunt me.. I have run it without the prop however, and wouldn't that reduce enough friction to allow for the increased bearing friction? Still, this doesn't explain why its so hard to start because the motor does turn over very easily with little resistance from the bearings when the spark plug is out.. I dont really care that it cannot idle because there is no nuetral gear and i can just start and go, but if i could just get it to easily start without taking 30 pulls (literally!) then i would be happy

 

[TOHATSU GURU]

Re: Tohatsu 2.5 Wont idle and Hard to Start

The more you go into this engine's history the more I think it should be in a junk pile. There is no way you could get to the bearings on the rods and they are shot. The only fix is a new crank shaft assembly and that is a couple of hundred by itself. Do yourself a favor and walk away from this engine.

 

[pvanv]

Re: Tohatsu 2.5 Wont idle and Hard to Start

TG is probably 100% on the mark. You will likely find that the flood waters did it in, and it's probably scrap. But... One other possibility. Check the condition of the o-ring at the carb base, where it slides onto the motor. That needs to be fairly supple. If not, you may have a vacuum leak there, which would contribute to a poor idle. A quick shot of ether spray in that area while running will verify that. If you have a 2.5A, the impeller is on the prop shaft, and easily replaced. But don't bother with that as long as cooling water is flowing from the telltale and you still have other items to fix.

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Well i believe you guys are about right.. ive had this motor for around 2 years and it never ran right.. plus now the pullstart has gone out. To the trash heap it goes!

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Just to add something usefull to this thread, I cut the top of my slide off today to allow full opening of throttle and it has much more power at full throttle. my model is ns2.5a for anyone else wanting to do this..

 

[Ns2.5a]

Re: Tohatsu 2.5 Wont idle and Hard to Start

Success!!!!!! Today in a last-ditch effort i pulled the carb and drilled out the main jet to 1/16 of an inch And she starts first pull with no choke!!!!