Re: 120HP (circa 1986) running slow
Well I have made some more discoveries.
When I removed the head the other day I pulled out the thermostat as well as the thermoswitch.
I brought both items to work today to test. I put both in a portable hotpot type personal water heater and had a thermocouple connected to a temperature meter and also had a digital multimeter connected across the thermoswitch and set on continuity mode to test that.
I slowly heated up the water and right around 160-165 F the continuity buzzer went off meaning the switch closed. Per the manual the switch is supposed to close between 160-170 F so that worked perfectly. The thermostat never opened and I heated up to about 170 F or so. So my thermostat is bad.
Now my thoughts turn to my maiden voyage. Bad thermostat equals overheated engine and engine just shutting itself off (which it did) due to the thermoswitch closing. I imagine there was also head gasket damage done at that time but I am not sure if the #3 cylinder part was broken at that time or not. There may have been head gasket damage done before that time but I am not sure if the previous owner had run the boat recently (after the thermostat sticking problem). Anyway there could have been head gasket damage done before I purchased the boat and I know there was damage done while I ran the boat.
I am still trying to figure out why the low RPM. I had 2 really rusty terminals for the spark plug wires so I am going to buy a terminal/boot replacement kit and fix those. I am thinking maybe I was getting intermittent spark on one or two cylinder due to bad connection (it was loose compared to the non rusty ones).
Anyway, I think I will just slowly go through everything and make sure it is right.
I have fuel out the carburetor body (coming right out the throttle bore) pretty much all the time, especially noticed while starting. What might cause that? I have read float level and also bad needle valves/seat. I may have to rebuild the carbs then.
