Re: Tohatsu 9.8 low rpm
The tachometer pole setting is set at 12. The prop I am running is the one that came with the motor. The only number I can find on it is 7.5. The boat is a Carolina Skiff JV13, 413 lbs. The 9.8 was chosen because the lakes I fish in have a 10 hp limit. I guess the RC box is set up correctly, because it seems to work fine. The dealer said he needed to rebuild the carb because the fuel was contaminated. When the dealer first put the motor on the boat, I didn't have a tachometer, I clocked out the boat with GPS at 15 mph. I wanted to install the tach because I wanted to see if I could change the prop to get more speed. When I go out now, GPS only clocks my boat at 9 mph at 3000 rpms. I never had the tach on the boat when I first went out, so I don't know what the rpms were, but according to the factory manual they should be 5600 rpms at wot.Could the ESG over rev RPM limiter been engaded somehow?
Check your owner's manual. Section 12, probably page 66. I may have misspoken. Some of these motors require the tach to be set at 6-pole. That's probably your issue with the 3,000 RPM WOT tach reading.
Your 7.5 prop pitch should be OK. If you load the boat down heavily, a little less pitch may perform better overall. But verify the tach first. You don't ever want too little pitch, or the motor will rev too high at WOT. The ESG should kick in if you try to go over 6,250 or so. The best WOT RPM for these is when they approach 6,000; 5,000 is OK... but... they run better overall if the prop is pitched to hit over 5,500 at WOT.
There is a possibility that the throttle cable from the RC box to the motor is mis-adjusted. Only 1/2 inch wrong could cause your issue, because the throttle lever would not be opening the carb plate all the way. You can check the adjustment yourself as follows: With the motor turned off, the control in Neutral, and the cowl off, disengage the "R pin" and nylon washer from the throttle clevis. Don't tinker with the shift clevis, since you said the control seems to be working OK. The clevis should go on and off the pin of the motor's throttle linkage freely, without having to move the linkage. That verifies that the control is set correctly at idle. Then set the RC control to full throttle, and operate the throttle lever on the motor to WOT. Again, the clevis should line up with the throttle link. If so, everything checks out, and you can reinstall the nylon washer and the R-pin.
