Re: Tohatsu MFS 9.8A3 difficult to restart after tilting up
The carb float is hinged at the back; therefore, assuming the float needle is OK, the carb should not flood when tilting. However, it could "wash out" with a little liquid fuel sloshing up into the passages. I've never seen that issue on a 9.8, though.
Sometimes, the throttle rod could be a little out of adjustment. That might prevent the "restart" position from opening the throttle plate enough.
A little explanation: Many carbed motors, Outboards, and 4-strokes particularly, can suffer from "hot soak" when the motor is shut down, and that's the primary reason for the "restart" position. When the motor is running, cold air comes into the carb, cooling it. When you shut down, the carb will get warmer, encouraging fuel to evaporate, resulting in a "too rich to start" condition. The fix for that is opening the throttle a little to admit more air, to help balance off the extra fuel.
In order to confirm the throttle rod adjustment, you need the motor off, the choke fully off, and the throttle at idle. Of course, the warm idle should have been set correctly (with a shop tach) first. The throttle stop screw should be in contact with the throttle arm of the carb. Then loosen the screw that retains the throttle rod to the brass swivel on the throttle arm of the carb, and remove all but a few thousandths of an inch of slack where the loop of the throttle rod meets the throttle crank pin, and re-tighten the screw in the swivel. The loop should be free, not binding, and have a tiny clearance to the pin. That way, when you rotate the tiller to "restart", the carb opens slightly, allowing some more air to compensate for "hot soak".
As an alternative, you can open the throttle a little past the "restart" position when starting, so that even if the throttle rod is a hair off, you have allowed enough air to restart.
Also... On the newer, EPA-rated tanks (the ones that have the gas gauge separate from the cap), the vent is not a "real" vent, but rather a 1-way check valve that will not allow air out of the tank below about 5 PSI. If you have one of those, the fuel pressure can go pretty high when the tank is sitting in the hot sun, which can promote minor flooding of the carb. That could also be part of your issue. Always a good idea to unplug the gas line from the motor if you will be shut down for a few hours; likewise, if you will be shut down for several days, run the carb out of fuel at the end of the day to reduce the chance of varnish buildup in the carb passages.
