adjusting 5hp 4cyl tohatsu

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outhere99

Seaman
Joined
Jun 13, 2008
Messages
62
I just started a new engine today. Fired right up, but wouldn't idle. I pulled the carb, and found some funk in the bowl. After cleaning everything (spray and compressed air) it ran better, but wouldn't idle. I don't know the year, but I think there are very few hours on this motor very clean).

Where is the idle mixture? The screw at the bottom of the float bowl seems to be just a drain.
 
pvanv

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,509
Re: adjusting 5hp 4cyl tohatsu

What's your model?

The newer carbs for 4/5/6 4-strokes are "non-adjustable" mixture. Probably need a good carb cleaning -- soaking -- rather than just a spray-job.
 
O

outhere99

Seaman
Joined
Jun 13, 2008
Messages
62
Re: adjusting 5hp 4cyl tohatsu

my model is a MFS5A. (possibly a 2000)

I gave the carb a good cleaning (3 times), and blow out with compressed air. Replaced the fuel filter with a glass inline type. Seem to run better, but the same issue has came back after running a bit.

I adjusted the float to level with the carb body (inverted), but that didn't help. Seems to be a fuel delivery issue, or fuel quality problem. I popped the fuel line off the carb, and it was pumping a healthy steam (pulses). Next will be fresh(er) fuel from a different line and tank...

Any other ideas?
 
pvanv

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,509
Re: adjusting 5hp 4cyl tohatsu

Sounds right. Test with fresh fuel. Likely still some junk in the wee passages in the carb. If all else fails, you may end up installing a new carb. BTW, the 6 hp carb will fit, and give you more output.

You could also check valve clearances to see whether some jerk set them too tight.
 
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