Tohatsu 3.5 Performance

Made a complete service maintenence, starts fine, some rpm hesitation at low idle, when placing forward gear engine stallls out, but maintains good rpm in neutral at all rpm range. Gear box has new gear oil and is not stuck, tested gasoline provided by owner seems old. What would be the max time in days to keep unethanol mixed gasoline to provide good engine performance ?

The service manual recommendfs "fresh", up to how many days it's considered fresh ?

Happy Boating

Re: Tohatsu 3.5 Performance

Thirty days is the given rule of thumb, but, it really depends on:

What the refiner put into the fuel.

What the refiner did not put into the fuel.

Where the fuel has been stored. (humidity, temp)

How robust the individual engine maybe.


An old 3.5 can handle more crappy fuel than a new one. But, the orifices are still pretty small and are still subject to more fuel issues than say a 100 hp engine of the same vintage.

Re: Tohatsu 3.5 Performance

I had a problem like that on my 8HP Honda, at end of summer. Would start more or less OK (tho I had to keep the throttle somewhat higher than what is normal) and would idle OK, but almost always stall when put in gear, unless I adjusted the throttle stop to a somewhat higher RPM. When I took the motor into my basement and worked on it, the pilot jet looked like its tiny in-line orifice was blocked. I removed the jets and pilot screw (not too much to remove on a simple card like that), soaked it all in carb cleaner and then used a very thin copper wire (one strand from a stranded electrical wire) to carefully clean the pilot jet orifice, and also blew every orifice I could find with compressed air.

Seems to work fine now, in my garbage can test tank - idles at 1200, and stays running when gear engaged, idling at about 1000 to 1050 in gear.

I'd discard the old gas, freshen it and use some StaBil (so everyone recommends, at least). May also want to change all the rubber fuel hoses, if it is old - I was told they dry out and can shed tiny particles. Both the ones from the tank to the engine (the primer bulb hoses) and the ones inside the motor, to/from fuerl pump and carb. And the fuel filter.

I am a newbie, and after I bought the Honda service manual, found it not too daunting a task.

Re: Tohatsu 3.5 Performance

The 3.5 was 2009 manufactured, seems an old gasoline issue, incrdible, you cannot trust owners when they say it's fresh , will give it a try with real pump fresh gasoline. Thanks both for the imput.

Happy Boating