Hissing and revs in idle

[GoPackGo78]

I'm hell bent on doing my own repairs....started the boat after winter and have the below issues. Looking for suggestions on what to check I will then use google and you tube and come back if I cannot fix it. 2002 bayliner 212 5.0 merc

Problem 1: took a bit to start but it did with some throttle juggling. There is a hiss when running....I do not recall it last year and it persisted throughout the day. Coming from below spark arrester and towards stern of engine. So far I've read it could be IAC, spark arrester not tight, power steering fluid (hose), vacuum leak, TKS. Any other ideas? Constant hiss engine sounds and runs good.
Problem 2: engine takes some running to not stall at idle. Once at idle it revs on its own occasionally (not real high rpm) but noticeable and random? Ideas?
Problem 3: ran the boat constant for about 20 minutes and became worried about the sounds decided to turn back. One the way back I saw the temp gauge jump up. I shut it down immediately. The engine did not die right away but sputtered for 2 seconds. We floated around for 20 minutes I could not see any obvious problem. Decided to start the boat. It ran like a champ but I didn't let it run more than 3 minutes in several interval s getting back. No problems the recast of the day but I'm sure this wasn't a fluke. What should I Check? Thoughts?

 

[tpenfield]

Sort of sounds like you have a fuel injected engine? Just not sure. Tell us the serial number of the engine as that will help with responses.

 

[alldodge]

Howdy

Agree, we do need the serial number

To me it kind of sounds like a TKS carb issue
When was the last time the impeller was replaced?

 

[GoPackGo78]

Carb for sure. Here is a link to video of the hiss.

https://youtu.be/3hgYYVSPIAw

It's running great today. No revs in idle no overheating. But the hiss is still there and I assume vacuum loss somewhere

 

[alldodge]

If the flame arrestor is correct its a 5.0 but unable to determine from the vid if its a TKS carb. If it is, then the TKS module may be stuck open.

Again could use the serial number to verify (its on the flame arrestor). or take the arrestor off and post a pic of it

 

[Mad Props]

All sounds like symptoms of a vacuum leak... a hiss, running rough, and running lean causes an engine to run hot... not too familiar with your setup tho

 

[GoPackGo78]

Only serial number legible transom om517559. It will not let me upload photos? How do I shrink them or is there a photo site you guys use?

 

[GoPackGo78]

https://ibb.co/kou28F
https://ibb.co/chZfvv
https://ibb.co/kywtFv
https://ibb.co/d22B2a
https://ibb.co/kj2YFv

 

[GoPackGo78]

To explain the pics outside the carb. The first pic that hose seems like it's doing nothing and is pretty smashed up. What is it? The pic on the side is over the valve covers and that little silver deal looks like a hose should be plugged into it

 

[Bondo]

Ayuh,.... Welcome Aboard,.... In img 519, the little hose under the big hose goes over the big hose to the silver nipple,...
It's a crankcase vent that probably goes to the flame arrester,...

The big puffy hose in img 517 is a heat shield, not a hose,... Hot exhaust gases past through the metal tube inside that heat coverin',...

 

[alldodge]

I'm seeing either a Rochester 2GC or Merc 2 bbl carb
The silver thing I believe is a PCV valve and if the small hose under the big hose has a vacuum being drawn thru when the motor is running, then it needs to be connected to the PCV valve

 

[GoPackGo78]

Problems seem to be solved. The occur valve I assume came off when I winterized. I used soapy water and found a second vacuum hose that was leaking cut it and clamped. All seems to be perfect. I ran her for 20 minutes no noises no revs. Thank you guys! Next problems will be a speedometer that doesn't work and flooring repair.

 

[GoPackGo78]

Occur above should say PCV