Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-11-2011, 05:33 PM   #1
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default 2000 2400 SCR Surging at High RPM

I have a 2000 2400 SCR that while idling and at speeds of less than 4000 rpm's seems to run fine. When I try and open it up past that it seems to surge or hesitate. The RPM's drop and then raise again. If i really hammer it and dont back off the throttle it will stall the boat. Has anyone seen this? I just bought the boat a couple of weeks ago and i know it was sitting for awhile. I changed my fuel seperator and cleaned the filter at the carb and it seemed to help for a little bit and then it went back to surging. I pulled the filter at the carb again and it seemed to solve it for a little while. Is this all related to my fuel line having stuff in it. Or could it be something else? Also what is a good cruising speed on these boats? I seem to do about 32mph at 3900-4000 rpms is this about right?
__________________

jlpete is offline   Reply With Quote
Old 08-11-2011, 07:18 PM   #2
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default

jl
welcome to the zoo.....first off..that is indicative of a weak accelerator pump....not getting enough fuel shot into the venturii while the throttle opens and causing a leaning condition....it could also be indicative of a slight vacuum leak....so...get a squirt bottle full of soapy water....with the engine idling...spray aorund the base of the carb....if there is no change at ALL to the idle...then it's definitely the acc. pump....


SP
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 08-11-2011, 07:50 PM   #3
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default

Thanks i will look into that.
jlpete is offline   Reply With Quote
Old 08-11-2011, 08:03 PM   #4
Admiral

 
ss3964spd's Avatar
 
Join Date: Jul 2009
Location: Fairfax Va
Posts: 1,512
Send a message via Yahoo to ss3964spd
Default

What engine, and does the engine have fuel injection or a carb (Im guessing carb).

As a test of the accel pump, if you are at idle and open the throttle quickly and far, does it hesitate then? Or is it only at upper RPM's when it hesitates.

When at higher RPM's and it starts to surge (speed up, slow down, speed up, slow down), will it continue to do so until you back off?
ss3964spd is offline   Reply With Quote
Old 08-11-2011, 08:17 PM   #5
Commander
 
Join Date: Aug 2010
Location: Purcellville, VA.
Posts: 295
Default

You stated that you replaced the water seperator and cleaned the strainer at the carb and "it helped". You then mentioned pulling the strainer at the carb again and it "seemed to solve it for a little while". So I have to ask, was it full of junk both times you did this or was there nothing noticable at all, just seemed to help after it was back together? Definitely seems to be starving for gas, could be just a bunch of junk clogging it up or could be what SP stated in the acc. pump. If you are seeing junk in the strainer and it runs good after cleaning it, you need to flush out the entire system (tank, lines, filters, carb.). Could just be dirt and such but could be the ethanol gummed up on you due to too much water in it (doesn't take much or too long of a time).
mcoffey is offline   Reply With Quote
Old 08-11-2011, 08:34 PM   #6
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default

Sorry guys it is a 5.0 mercruiser carb. If I back off the surging stops and i can re accelerate. I can put it in nuetral and rev it up to about 4800 until it cuts out but i think that might be the rev limiter.
jlpete is offline   Reply With Quote
Old 08-11-2011, 08:36 PM   #7
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default

And there is some residue in the strainer not much but definitely some!!
jlpete is offline   Reply With Quote
Old 08-11-2011, 08:42 PM   #8
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Thumbs up

Quote:
Originally Posted by jlpete View Post
Sorry guys it is a 5.0 mercruiser carb. If I back off the surging stops and i can re accelerate. I can put it in nuetral and rev it up to about 4800 until it cuts out but i think that might be the rev limiter.

you don't have a rev limiter in the carbed version.....

surging (reving up and down) is usually water in the gas....but total hesitation or flat spotting from acceleration....is caused by the carb leaning out...which is the accel. pump...



SP
__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 08-11-2011, 08:45 PM   #9
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default

Thanks I will let you know if it helps!
jlpete is offline   Reply With Quote
Old 08-16-2011, 04:08 PM   #10
Lt. JG
 
Join Date: Aug 2011
Location: Bremerton WA
Posts: 20
Default

Ok so i pulled the air horn off and looked at the acclerator pump, i didnt change it because i couldnt find one locally. i then reassembled the carb and filled up with gas and also put in some fuel clean. I ran with out any problems for about half a tank as soon as it got around half it started cutting out again. Do you still suspect the accelerator pump? I have one on order so will change it anyways. Just making sure this new info didnt change anyones thoughts?
__________________

jlpete is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 06:59 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.