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Tohatsu 2006 3.5 not reaching WOT

santamariah95

New member
Sorry if this post appears twice. I'm getting mixed results posting for my first time on this site.

I've got a 2006 3.5hp Tohatsu that starts easily, runs fine at low speed thru mid-throttle then tops out before hitting wide open throttle (WOT). It feels like there's a governor preventing the o.b. from opening up.

Steps I've taken:
  • Drained fuel tank and replaced w/new 91 octane fuel
  • Changed engine and transmission oils
  • Soaked & cleaned carb in Sea Foam; then replaced innards w/rebuild kit. Blew out orifices w/canned compressed air
  • Replaced sprk plug
  • Replaced inline fuel filter and on/off fuel selector switch
There didn't appear to be any varnish/fuel buildup on the inner workings of the carb, though there was a "gobb" of something in the float bowl.

I'm running the o.b. in a barrel and without the propellor. I've seen reference to an ESG (high rev limiter) but god help me find out where the heck this is if it's even there. I've prepped other 2-stroke OBs for years this way and never run into a WOT problem like this one except for water in the fuel.

Very frustrating as I've got a new(er) 19 Rhodes to get into the water soon and this issue is just dragging on.

I welcome any thoughts/suggestions concerning something I may have overlooked. Hate like heck to take this to dealer if I can help it. Money's running low :( for this small luxury this year.

Many thanks in advance;
Waiting it out in Massachusetts
 
As TG suggested on iBoats, You likely have an ignition system to check out. The Factory service manual would be a good idea here.

Also...

These motors run just fine on 87 - 89 octane. 91 is unnecessary.

They sip the fuel so slowly... Changing out the fuel cock and lines seems unnecessary unless they are damaged.

A "gob" in the carb indicates that there may have been some contamination, possibly a "gel" of ethanol and stabilizer. Seafoam is not a proper carb cleaner, BTW. If you suspect a carb varnish restriction, the only relaible method is to soak in a proper carb dip and blow out with shop air. However, that sort of varnishing restriction usually affects slow speeds more than WOT.

Is your float height correct? Is the needle/seat flowing well? If not, you could have a slightly lean condition, which might limit WOT. What WOT speed is indicated on your tach?

Verify that the oil is not overfilled -- not even a drop. Excess crankcase pressure from overfilling will limit WOT.

These motors do not have a discrete ESG hardware module. That's why you can't find one. The spark advance profile is designed into the CD module.
 
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