1983 Mercruiser 454 High Idle

[aquafresshness]

Okay so here's the skivvy. The port motor idles at around 1300-1500 when in neutral. Once I put both motors in gear they both idle just under 1000 and nice and even and smooth. But when I pull them both out the port motor revs back up to 13-1500.

When I first bought the boat they both idled nicely, but 8 weeks later, recently it's always been a little high. I unplugged the electric choke and it doesn't change anything.

I searched on here and read about some ITS or TIC sensor or something?? Does this apply to my motor? Any ideas why it's idling high?

They're 4 barrel holley carbs.

 

[chiefalen]

Re: 1983 Mercruiser 454 High Idle

They are supposed to idle at 650-700. They always idle that fast from the get go.

Shifting got to be taking it's toll on the drive.

Bye the way what sorta drives do you have on the back.

If i'm reading this right you can't get it to idle lower, and still run, that means if i'm right, that the carbs are dirty the idle is messed up and a rebuild on the carbs are in order.

 

[aquafresshness]

Re: 1983 Mercruiser 454 High Idle

They're TRS outdrives I'm told. They're relatively new Holley 4 barrels so I don't think that's the prob. I'm pretty sure it has something to do with the butterfly flap staying all the way open and not closing at idle.

 

[legoman67]

Re: 1983 Mercruiser 454 High Idle

i would say your outdrive is putting exessive load on the engine for idling. Is this happening in the water? or out of the water? Have you checked all your throttle linkages? maybe something has gone a stray.

When you give it further throttle what happens?


Also are these the same engines you were asking about removing? then decided you didnt need to?
Please fill in the story.

 

[Don S]

Re: 1983 Mercruiser 454 High Idle

Disconnect the cables from the carb and see if the idle comes down. If it does, adjust the cable so the linkage is preloaded slightly so the carb linkage is against the idle stop screw.

 

[aquafresshness]

Re: 1983 Mercruiser 454 High Idle

Disconnect the cables from the carb and see if the idle comes down. If it does, adjust the cable so the linkage is preloaded slightly so the carb linkage is against the idle stop screw.

Boom! There it is I didn't even think of that.. I'll try that in the morning.

 

[aquafresshness]

Re: 1983 Mercruiser 454 High Idle

i would say your outdrive is putting exessive load on the engine for idling. Is this happening in the water? or out of the water? Have you checked all your throttle linkages? maybe something has gone a stray.

When you give it further throttle what happens?


Also are these the same engines you were asking about removing? then decided you didnt need to?
Please fill in the story.

This is not the same boat that i wanted to pull a motor on. This is my '83 with both motors running great. It does it in and out of the water. It runs perfectly, no problems whatsoever. It just seems like the idle sticks a little high. It revs fine in idle and runs perfect under a load, never stalls. It would idle lower RPM just fine if I could get it to come down... It's not like it wants to die, it just won't RPM down. It has no issues of trying to stall... it just won't slow down.

 

[Bondo]

Re: 1983 Mercruiser 454 High Idle

They're 4 barrel holley carbs.

Ayuh,... Merc never used Holleys,...
So I'd Guess that somebody didn't finish the adjustments when they were swapped on...

Your Idle should be about 600/ 700rpms at idle, in gear, in the water...