RPMS not coming down at idle

J

Johnshan1

Senior Chief Petty Officer
Joined
Apr 15, 2003
Messages
739
2000 Volvo 5.7L engine, just started it for the season and have an issue already.

I start the boat and it idles at 600 rpms give or take. If I increase the throttle it revs up, but doesnt rev back down below 2,000 rpms. I cant get it to drop.

If I shut it off and restart it is at 600 rpms again. Advance the throttle, same issue.

Any ideas? Butterfly seems like its moving just fine in the carb, nothing stuck.

Choke issues?
 
cribber

cribber

Lieutenant
Joined
May 29, 2008
Messages
1,338
Re: RPMS not coming down at idle

Have you checked all of your vacuum hoses? It could be a cracked vacuum advance hose causing it to idle higher since it sounds like it never backed the advance down. Just a SWAG...
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: RPMS not coming down at idle

Is the throttle linkage hooked up to the carb? Check it. If it is, disconnect it and see if operating the carb itself will come back to idle.


It could be a cracked vacuum advance hose causing it to idle higher
Click to expand...

Boats, DO NOT have vacuum advances, or at least they better not have.
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,525
Re: RPMS not coming down at idle

Ayuh,... Could be a Vacuum Leak though....
 
cribber

cribber

Lieutenant
Joined
May 29, 2008
Messages
1,338
Re: RPMS not coming down at idle

Don S said:
Is the throttle linkage hooked up to the carb? Check it. If it is, disconnect it and see if operating the carb itself will come back to idle.


Boats, DO NOT have vacuum advances, or at least they better not have.
Click to expand...

Like I said it was a SWAG my part... Thanks for jumping in there Don S with the correct info!!! ;)
 
J

Johnshan1

Senior Chief Petty Officer
Joined
Apr 15, 2003
Messages
739
Re: RPMS not coming down at idle

Thanks guys.

Do I even have vacuum hoses on this engine? I don?t even recall.

I haven?t been able to dive into this yet, but I do not believe I have a throttle cable issue because again, if I shut it off and restart, all is well without touching any throttle at any time.

I will remove the cable and check the operation of the carb asap (I hope I can do this tonight).

Where would typical vacuum leaks be if that was the problem?

Thanks.
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,525
Re: RPMS not coming down at idle

Where would typical vacuum leaks be if that was the problem?
Click to expand...

Ayuh,...

Around the base of the Carb, or where the intake meets the heads...
 
J

Johnshan1

Senior Chief Petty Officer
Joined
Apr 15, 2003
Messages
739
Re: RPMS not coming down at idle

Strange. Being a well maintained 2000 model year I am hoping it is something simple.
 
J

Johnshan1

Senior Chief Petty Officer
Joined
Apr 15, 2003
Messages
739
Re: RPMS not coming down at idle

Dunno what the exact problem was, I took a wrench and tapped the throttle linkage and it came right back down. I greased everything and adjusted the linkage a touch to close the throttle a bit more at idle. Its strange because the butterfly/throttle plate was already seated when the RPMS were at 2000+

Will try it again tomorrow.
 
You must log in or register to reply here.
Top