High rpm idling-gctid821178

[Guest]

Went out boating with my wife as one of our usual days.. before went out boating, I used ear muffs and fired it up and let it ran for good 5 mins. It was big running for first 15 seconds which it went smooth afterward. So, went to lake and fired it up and all good but noticed the rpm- way high. Seems like I ll have to adjust the idling screws to get proper rpm. But, what throws me off, I didn't do any adjustments since I bought the boat 3 years ago.

https://youtu.be/XEiakHYJ8sM

[Pcpete]

Before you touch the adjustment, it sounds like you may have a sticky high idle cam (usually connected to the automatic choke) that needs some attention. It's probably just one of those things you apply some penetrant and work it with your fingers to get some junk out of where it rides on the shaft.

Go with easy first.

[Guest]

Great! Will give it a shot and see from there. I sure it is a just small issue and easy fix since summer isn't over yet

Will update you guys.

[Guest]

05 Mercruiser, does this not have a TKS carb?

[Guest]

Yes, I believe my carb is tks? I just removed the arrestor to see the carb, its wide open. it fired up with one start but came up to 800 then 1k for good 5 mins...

[Guest]

TKS carb has no choke plate, has bypass port controlled by a solenoid. Problem could be a wire, a fuse (there is a 20amp inline in this circuit), the solenoid itself or one of two sensors (temperature sensor and oil pressure switch on the 3.0, fuel pump on 4.3 and up).

[Guest]

Yeah, thanks for correcting me with the carb model. Yes, looks like my carb isn't tks... so, I found a picture of carb that exact one I got.

[Guest]

OK, if choke plate is opening all the way, go with what Pete said.

[Guest]

Is it normal to see the choke plate wide open even it's not on? I started it up and choke plate stayed opening but when turning it off, it stays open.

Also, I checked and cleaned the cam and seems got my boat back to normal as before but, definitely need to adjust it lower to 700s. I don't like to see it idling with 1k-1.3k so, guess I'll just need to do is adjusting the cam idle screw to get it to 700s at the neutral position?

T

[builderdude]

It is normal for the choke plate to stay wide open just after shut down. As the engine and the choke thermostatic spring cool down the choke plate will return to almost closed.

[Guest]

Great, I will test it again this weekend but in the lake.

Here's short video clip of my motor running on the earmuffs...

https://youtu.be/22iRAV0dAnQ

[Pcpete]

I don't believe that motor is idling over 550 rpm in your clip. On the back side of the tach is a dial that is marked 4,6,8!with a very small screw driver slot in it. Try rotating the dial to see if it's a bad connection. It's odd that it would be reading high because of the dial setting, but I've seen it. I have a timing light with a tach built in that I used on my 4.3's. It was well worth the investment at the time.

[Chief_Alen]

in the water on a warm engine you should be around 600-650 rpm, the lower the better if it idles good.

On the trailer with muffs idle around 800-850 is good in the water you lose 200 rpm.

To the carb choke.

Cold engine before starting advance the throttle fully to the stop twice, should reset your choke closed, if it does not you ether have a choke that has been dismantled ...

( common for boats in FL and other warm climates ) or there is a problem with the linkage.

Saw the video that is a engine idling well and i saw it was around 800 + rpm the boat was on the trailer ? Seems it was.

These old eyes are going i will watch the video again.

[Guest]

As for new update today...

Took my boat out for a cruise day with my wife and brother in law's family. Fired her up at the lake and the rpm stays 700-800 for good 7-10 mins then surged up and down between 1k-2k so but the engine running was smooth which, I asked my niece who can hear, she said all smooth. So, I cleaned the sticky part, nothing. So, I decided to just fk it and go for a cruise ride and see from there. when I hit 15-20 mph, it hits around 4.9k-5.2k which isn't normal. So, I decided to look up behind the RPM gauge, all good except one white plastic piece which wasn't aligned properly so, I played with it and rpm went back to normal as day one I bought it.

Happy Labor day you guys!

Sad thing is... putting her away in the canopy for months until spring 18'

Cheers!

[Ion66]

Way too early to put a boat away!!