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I'm sure this question has been asked before, however, Tohatsu 50 at full throttle after awhile will just loose power, as if it's either starved for full or there is a mixture problem. Move into neutral, and then slowly bring back up to speed, happend intermittenly. Any ideas?

I have a Tohatsu 90 and had some weird performance problems.

The guys on the board pointed out the vent on gas tanks. I kept having problems on one of my tanks and it turned out that the vent was closed. THe other tank's vent was open and no problems. You might want to check that.

What model MAc do you have?

I just ordered and received the repair manual for the 1992 ~ 2000 Nissan outboard. This would be the older engine with three carboretors. In the troubleshooting section it addresses "Bogging on acceleration".

Possible Reasons:
~~~~~~~~~~~~~
Faulty accelerator pump
Old or contaminated fuel
Fuel pump malfunction
Plugged carboretor jets
Improper carboretor adjustment
Blocked fuel filter
Closed fuel tank vent
Air leakage in the fuel hoses
Fuel leaking from system
Misadjusted throttle position sensor
Faulty electrothermal valve

~~~~~~~_/)~~~~~~~~~~
Rich Plumb, "Plumb Crazy"
Covington, WA, 26X

Crap in the carbs. (a diagnosis, not a suggested course of action) I pulled mine a couple weeks ago and had them cleaned.
Pretty easy to do and fixed it right up.

0) remove the fuel hose.
1) remove plastic air cleaner thing.
2) unscrew the base of the plastic air cleaner thing.
3) don't drop nuthin in the water.
4) swat the wasp that is trying to land on your nose. (repeat as needed)
5) unbolt the oil tank.
6) remove all linkages and fuel lines.
7) remove the 2 bolts that hold each carb in place.
8) try to remember where all the linkages went, and which carb went where.
9) It would be helpful to have already order the carb bowl gaskets in case the old ones rip.
10 take the carbs to your friendly marina mechanic to solvent rinse out the carbs in a parts washer for a few hours. He will also open up the carb bowls to remove the gunk.
11) reverse the steps to reinstall.

Buy a fuel line filter if you don't already have one.

does it bog on all tanks.........

the engine is very picky about fuel supply pressure.....check your tank squeeze bulbs and verify unrestricted flow prior to removing carbs...... Especially those portable tanks utilizing strainers in the supply tubes.

Then progress to the carb inspection and cleaning.

1997. If I run at WOT, the overheat buzzer alarm comes on after a few minutes and slows down the motor until the buzzer goes off. If I run at 90% or so, the overheat buzzer doesn't come on.

Is this what others are seeing with the Tohatsu/Nissan?

Luke Varanko wrote: ... at full throttle after awhile will just loose power, as if it's either starved for full or there is a mixture problem ...

Well the rule of thumb states that 90% of such problems are fuel related. In the rare cases tho - it can be electrical. I once had a coil that faulted at very high cycles, worked okay in mid-range.

Might coudda bin the capacitor too I just swapped them both & problem disappeared.

Miami,

The overheat buzzer (actually the sensor) was faulty on a bunch of the Tohatsu 50s of that vintage. several others reported problems and then I had the problem too. the sensor was too sensitive and would prematurely indicate overheating. I ordered a replacement and had the same problem again so finally just removed mine entirely.

The recommended replacement was for one of their large motors that was supposed to be good, but I had the same problem with it.


I just try to keep an eye on it to make sure the water is still coming out of the telltale etc. Maybe this is not a good practice, but I got tired of the stupid motor going into SLO mode.

Then again, maybe it is really overheating, so I would at least make sure the water pump and thermostat are not past replacement dates, the pee hole is squirting, and pull the cover and see if you think the motor is really overheating or not.

The overheat sensor is a little metal round thing about the diameter of a 12gauge shotgun shell with a sky blue wire running from it. It is held into a well on the engine with a simple little bolt that holds a metal retainer over it. It is the only sky blue wire on the engine, so it should be easy to find. .

Is there a capacitor on the 97 Tohasu 50? If so , I should probably change mine just for good measure.

Thank you very much for the info regarding faulty temp sensors, Craig.

I decided not to remove the temp sensor totally because I wanted it to still work, but not be as sensitive.

So I modified it.

I unbolted the sensor from the powerhead and put a approx 1/8 inch spacer in the bottom of the hole. I fashioned a spacer from some 14 guage electrical wire in the form of a loop. You want to leave the center of the spacer open. You want an air gap between the sensor metal face and the bottom of the hole it resides in. That air gap retards the heat transfer to the sensor.

With the 1/8 inch air gap, I estimate that I raised the temp that it will trip the alarm by probably 20 degrees higher or more.

Tried it yesterday, and I get no more overheat buzzer at WOT.

Plenty of water comes out of the pee hole.

I don't run at WOT a lot as it burns a lot of fuel, but I didn't want the darn overheat sensor killing my power in an emergency when I need WOT to get out of a jam.