Tohatsu 5hp, 2 stroke running problem

[sgjfrods]

Hi all, I have a 2 stroke Tohatsu motor with an external fuel tank that was running poorly and always needed the choke to run. After reading other threads i started with the simple solution first and got fresh fuel with the right mix of high grade marine oil additive. This did not solve the issue.

I then proceeded to remove the carb, take it to bits and clean it up with aerosol carb cleaner, it did look a bit "varnishy" inside prior to cleaning indicating things may well have been gummed up. I unscrewed the brass screws with small jets and blew this out with carb cleaner. I have now re-assembled it and put it back on the motor.

However, now when i squeeze the primer bowl fuel comes out of the hole on the attached image that is inside the air intake. In addition, when i gently pull the starter cord a small amount of fuel flows out through the choke air inlet. Is this normal? I.e. can you over prime the fuel system and this is "an overflow"?

Many thanks for any help, i have disassembled and reassembled the carb again to check i haven't messed anything up and i am pretty stumped with this one .

 

[sgjfrods]

The last two images failed to attach.

 

[sgjfrods]

Annotated image for clarity,

Any Help is very much appreciated!

 

[coveman]

No doubt others with a better knowledge than me will be along soon but it may be worth checking that the main jet is in fact clean. When cleaning my carb in a similar fashion to you, even though I left the jet soaking in carb cleaner, it needed a poke with some soft copper wire to free the sticky varnishy deposit. I used one strand from a length of stranded copper wire and when held to the light the difference was huge and the motor started and ran ok - may be worth a try?
Not sure about the fuel running out of the holes but at least it proves fuel is getting to the carb. The fact it only runs on "choke" would perhaps indicate lack of fuel through the jet and the air/fuel ratio being incorrect without the choke engaged.

 

[sgjfrods]

Many thanks Coveman, I have done exactly as you have said when initially cleaning the carb and carefully pushed very fine copper wire through the tiny holes on the main jet. The engine now doesn't want to fire at all and therefore i cannot test whether the engine runs better now with a clean carb. I do not want to carry on trying to start it as i believe there must be a problem with the fuel running out of these holes. I am pretty sure no fuel ran out of these places before i took off the carb but i may have missed this.
Any guidance on this is much appreciated!

 

[VicS]

Hi all, I have a 2 stroke Tohatsu motor ...............................

However, now when i squeeze the primer bowl fuel comes out of the hole on the attached image that is inside the air intake. In addition, when i gently pull the starter cord a small amount of fuel flows out through the choke air inlet. Is this normal? I.e. can you over prime the fuel system and this is "an overflow"?

Any guidance on this is much appreciated!

Not absolutely sure but the hole may be just an air vent (Like you have a breather or vent on a fuel tank)
You should not be able to over fill the carb and it is not normal for fuel to flow out of the air intake when you crank the engine

Your trouble now is that the float operated needle valve that controls the flow of fuel into the carb is not seating properly,

It may be damaged, there may be some muck preventing it from seating, the float may be sticking Or you may have put something back together incorrectly.

I am looking for a daigram of the carb .... what HP is the engine ... 4 or 5 ? and what year?

 

[coveman]

Or you may have put something back together incorrectly.

Yes, maybe the needle is upside down?? I don't know if they are all much the same but the needle on my motor is secured in a slide on the float bracket with the point pointing down to seat in the base - 5hp motor according to the title.

 

[VicS]

Yes, maybe the needle is upside down?? I don't know if they are all much the same but the needle on my motor is secured in a slide on the float bracket with the point pointing down to seat in the base - 5hp motor according to the title.

Yep overlooked the HP in the title

Pointed end of the needle should be UP into the seat . This one has a small clip to link it to the float arm. This is normal with soft tip needles as they tend to stick on the seat otherwise.

Parts lists and diagrams
https://www.tohatsu.us/docs/pdf/Parts Catalog M5B (2003) - (00221005-6).pdf

 

[sgjfrods]

Thanks so much for this, i will check out the float needle. Just for clarity does this mean the pointy end of the needle is pointing down (i.e. towards the ground?).

 

[Billows]

To test with the bowl off blow through the fuel pipe . Raising the float with your finger should shut the air off
Pointy end usually points up

 

[coveman]

Thanks so much for this, i will check out the float needle. Just for clarity does this mean the pointy end of the needle is pointing down (i.e. towards the ground?).

No, as VicS mentioned, the pointed end should be placed up into the housing so the other end, ( square on my carb), is attached to the float. When you take the float off the needle can easily drop out and cause a bit of head scratching as to how it was originally

 

[sgjfrods]

I took the carb to bits again last night and rechecked the float. Re-assembled it and it started up lovely. It wasn't obvious but the needle mustn't have been seating properly! Many thanks for all of your help!

One more thing . This outboard has an external fuel tank with a push fit clip onto the outboard. I cannot see any way to turn off the fuel supply short of just un clipping the external fuel hose. How are other outboard engines configured? I was expecting to see some kind of valve to switch off the supply.

I understand you should run the carb dry before storage to prevent things becoming gummed up by evaporating fuel again and figured there must be a easy way to do this.

Many thanks again.

 

[VicS]

I took the carb to bits again last night and rechecked the float. Re-assembled it and it started up lovely. It wasn't obvious but the needle mustn't have been seating properly! Many thanks for all of your help!

One more thing . This outboard has an external fuel tank with a push fit clip onto the outboard. I cannot see any way to turn off the fuel supply short of just un clipping the external fuel hose. How are other outboard engines configured? I was expecting to see some kind of valve to switch off the supply.

I understand you should run the carb dry before storage to prevent things becoming gummed up by evaporating fuel again and figured there must be a easy way to do this.

Many thanks again.

Internal fuel tanks usually have a fuel cock to shut off the fuel

With external tanks you usually just disconnect the fuel line.
I normally do that when I am not going to use the engine again for a week or so. Pick up the mooring, disconnect the fuel line and stow the tank. Let the engine run until it peters out . Raise the engine and secure.

 

[sgjfrods]

That's great, thank you so much.