2007 Tohatsu 4HP 4stroke to 6HP

[Gogheenu]

Fuel gelled in carburetor. Took it apart and boiled it. While tapping the float pivot pin back in, I snapped one of the ears off so I have to get a new carb.

I read some old post about upgrading to 6HP carb. Can that be done on my engine? Model MFS4BD 3H9

If so, does anyone have a good part number and a source? No dealers near me.

 

[pvanv]

Re: 2007 Tohatsu 4HP 4stroke to 6HP

The pivot pin only goes in 1 way. There are serrations at one end. That may be why you cracked the casting. A service manual would have been less expensive than a new carb, BTW.

Yes, you can run an MFS6 carb on an MFS4, and you will get 6 hp. Any Tohatsu/Nissan dealer can provide you with one, even me.

The precise EPA-rated carb for the 4/5/6 B-model (would be required if a warranty repair) is
3AU032000M CARBURETOR, MFS /NSF6B $106.70

The carb for the 4/5/6 A-model is also still available, and will work better overall.
3R4032001M CARBURETOR ASSY, MFS/NSF6A2 $106.70

Gel junk in the carb is due to water in the fuel, possibly exacerbated by E-10 fuel. Always get the gas out of the carb of the motor is going to sit for more than a week or 2. You can run the carb dry, or better yet, open the drain screw to fully empty the bowl.

 

[Gogheenu]

Re: 2007 Tohatsu 4HP 4stroke to 6HP

Gel in gas was caused by putting Stabil in the gas. It gelled up 2 outboards, a weedeater and my 4 wheeler. Something about the alcohol in the gas. I will never use it again.

Yes the pin has serations on one end. Due to that, one of the ear holes is slightly larger than the other. The extra size allowed the pin to get out of alignment. The ear snapped off because I failed to support the ear when I tapped the pin with needle nose. Should have had my finger under it.

Anytime I buy a new piece of equipment, one of the first things I do is get a service manual. I have them for both my 4 strokes.

You stated an older model carb would be beter. Why do you think so?

 

[TOHATSU GURU]

Re: 2007 Tohatsu 4HP 4stroke to 6HP

The A model carb had a less stringent EPA requirement. It isn't as easy for a consumer to screw it up through lack of maintenance and works very well on the B model engine.