You need to learn that the water from the tell tale does not even circulate through the block or the thermostat !!----It tells you that the water pump is working.----It does NOT INDICATE that motor is cooling properly.
The tell tale should show water right after start-up.----Thermostat is not involved with tell tale.----Tell tale is plugged.----Or not enough water in your test bucket.----Or needs new impeller if it has not been done for 5 years.
So you are raising the fast idle lever.------Are you pushing the key in or pushing a button for choking while cranking it over ???----Excessive cranking can easily damage the starter so be careful.