Reply
 
Thread Tools Display Modes
 
Old 05-26-2017, 11:31 AM   #1
Veteran Member
 
schrater's Avatar
 
City: Vancouver, WA
Country: USA
Vessel Name: Matilda
Vessel Model: Ponderosa (CHB) 35' Sundeck
Join Date: Sep 2016
Posts: 38
Dinghy outboard problem

I have a Johnson 8hp outboard on my small RIB. It has been working great for a long time, until last week. After running with it for about 30min, it suddenly dropped down to idle speed and would not accelerate. It did not die, it was still getting fuel, still had a spark, etc. But even turning the throttle full open would not give it much power. And even in neutral it would not rev very high at all.

I checked simple external things like the fuel line and the prop, but everything looked fine. I'm wondering what troubleshooting I could do to narrow down the cause of this problem. Or maybe the cause is common and already well-known?
__________________
Advertisement

schrater is offline   Reply With Quote
Old 05-26-2017, 11:52 AM   #2
Ted
Guru
 
Ted's Avatar
 
City: Campbell River
Country: Canada
Vessel Name: Okisollo
Join Date: Apr 2012
Posts: 577
Quote:
Originally Posted by schrater View Post
I have a Johnson 8hp outboard on my small RIB. It has been working great for a long time, until last week. After running with it for about 30min, it suddenly dropped down to idle speed and would not accelerate. It did not die, it was still getting fuel, still had a spark, etc. But even turning the throttle full open would not give it much power. And even in neutral it would not rev very high at all.

I checked simple external things like the fuel line and the prop, but everything looked fine. I'm wondering what troubleshooting I could do to narrow down the cause of this problem. Or maybe the cause is common and already well-known?
You don't mention it in your external checks but, when you turned the throttle handle did you see the the throttle on the carb open?
Check the throttle "vane" inside the carb, it may have come loose on the shaft.

Ted
__________________

Ted is offline   Reply With Quote
Old 05-26-2017, 12:13 PM   #3
Senior Member
 
ragin cajun's Avatar
 
City: Lafayette, LA
Country: USA
Vessel Name: Miss Puddy
Vessel Model: 44' Nova
Join Date: Dec 2014
Posts: 245
I'm assuming this is an older 2 stroker 8hp. Sounds to me the high speed jet in the carb is gummed up. Take apart the carb and clean it well.
ragin cajun is offline   Reply With Quote
Old 05-26-2017, 12:58 PM   #4
Guru
 
djmarchand's Avatar
 
City: East Greenwich Yacht Club, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,540
As others have noted, first check that the throttle plate in the carb is moving when you twist the throttle. If it is then as noted above, it is probably gummed up with ethanol related stuff.

Remove and dissasemble, then soak in a can of carburetor cleaner that you buy at an auto parts store. I have an 80% success rate with this procedure.

David
djmarchand is offline   Reply With Quote
Old 05-26-2017, 12:59 PM   #5
TF Site Team
 
dimer2's Avatar
 
City: Houston
Country: USA
Vessel Name: Baobab
Vessel Model: Bayliner 4788
Join Date: Aug 2013
Posts: 1,983
Quote:
Originally Posted by ragin cajun View Post
I'm assuming this is an older 2 stroker 8hp. Sounds to me the high speed jet in the carb is gummed up. Take apart the carb and clean it well.
Ragin Cajun is probably right but seeing as it is running, I would add a carb cleaner to my fuel and see if it cleans up before pulling the carb.
__________________
No one who achieves success does so without acknowledging the help of others.
dimer2 is online now   Reply With Quote
Old 05-26-2017, 01:09 PM   #6
Senior Member
 
ragin cajun's Avatar
 
City: Lafayette, LA
Country: USA
Vessel Name: Miss Puddy
Vessel Model: 44' Nova
Join Date: Dec 2014
Posts: 245
Quote:
Originally Posted by dimer2 View Post
Ragin Cajun is probably right but seeing as it is running, I would add a carb cleaner to my fuel and see if it cleans up before pulling the carb.
This is worth a try...Sea Foam works really well.
ragin cajun is offline   Reply With Quote
Old 05-26-2017, 01:55 PM   #7
Senior Member
 
AKDoug's Avatar
 
City: Kenai, Alaska
Country: USA
Vessel Name: Melanie Rose
Vessel Model: 1999 Willard PH
Join Date: Feb 2013
Posts: 494
Another for plugged jet, do a uTube search for how to clean your carb and do it. I had a bugger in my jet, probably because I was carrying the fuel tank on the swim platform and a little water migrated into the tank.

Got to love uTube :-)
AKDoug is offline   Reply With Quote
Old 05-26-2017, 03:40 PM   #8
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,242
Quote:
Originally Posted by dimer2 View Post
Ragin Cajun is probably right but seeing as it is running, I would add a carb cleaner to my fuel and see if it cleans up before pulling the carb.
Quote:
Originally Posted by ragin cajun View Post
This is worth a try...Sea Foam works really well.
Or just get the Sea Foam spray and use it directly into the carburetor. Short bursts vs a steady stream seem to work pretty good. You want to keep the engine running. I don't have the patience to mix the SeaFoam with the gas. I want it to work now!
Larry M is offline   Reply With Quote
Old 05-26-2017, 03:44 PM   #9
Guru
 
City: Full Time Cruising East Coast
Country: USA
Vessel Name: Meridian
Vessel Model: Krogen-42
Join Date: Aug 2011
Posts: 683
Sea foam directly will not necessarily clean a clogged jet as the spray is upstream of the clog. But worth a try.
__________________
-------------------------
Terry
Meridian
KK-42097
meridian is offline   Reply With Quote
Old 05-26-2017, 04:54 PM   #10
Guru
 
motion30's Avatar
 
Join Date: Jan 2010
Posts: 721
Something to try and has on occasion work for me. Pull the fuel connector and run the motor dry. Tilt the motor up and pump the fuel ball. Start it and see how it runs if that will not clear your main jet the carburetor needs to be removed to disassembled and manually cleaned. You can spray anything you want in the carburetor it will not clear the debris in your jets
motion30 is offline   Reply With Quote
Old 05-26-2017, 04:57 PM   #11
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 14,531
First, check the fuel...if it phase separated from lack of use...a carb deep cleaning or rebuild is necessary.

Pour the gas out and see if it phase separated.
psneeld is online now   Reply With Quote
Old 05-26-2017, 05:06 PM   #12
S41
Veteran Member
 
City: S. Puget Sound
Country: US
Vessel Name: Shaleen
Vessel Model: Symbol 41 Sundeck
Join Date: Aug 2015
Posts: 68
I had the same problem on my 1 year old 4 stroke 4HP Tahatsu.

The solution was looking at a you tube video to know how the carb came off... Then, I pulled the carb off, removed the jets, cleaned the jets by just blowing the gunge out, cleaned the inside of the bowl with paper towels, put it back together and added fresh non-ethanol gas.

It took longer to pull the outboard off the dinghy onto the dock and put it back onto the dinghy after it was all cleaned then it took to clean the carb. It has ran great ever since.
S41 is offline   Reply With Quote
Old 05-26-2017, 05:09 PM   #13
Guru
 
City: Sydney
Country: Australia
Join Date: Jul 2015
Posts: 1,135
Short answer REED VALVE
gaston is online now   Reply With Quote
Old 06-04-2017, 05:34 PM   #14
Veteran Member
 
schrater's Avatar
 
City: Vancouver, WA
Country: USA
Vessel Name: Matilda
Vessel Model: Ponderosa (CHB) 35' Sundeck
Join Date: Sep 2016
Posts: 38
Thanks to all who replied with helpful suggestions on this. For those following along at home, the carburetor actually ended up being very clean, but a small plastic part called the "cam follower" had snapped. This meant the throttle handle would turn without ever opening up the high speed jet. $10 replacement part and problem solved!
Click image for larger version

Name:	IMG_5795.JPG
Views:	32
Size:	29.0 KB
ID:	65431
schrater is offline   Reply With Quote
Old 06-07-2017, 08:16 AM   #15
Guru
 
City: Fort Myers
Country: USA
Join Date: Jul 2013
Posts: 898
Good news, thanks for posting the results.

Ted get's the award for closest diagnoses over the internet!
Marlinmike is offline   Reply With Quote
Old 06-13-2017, 02:27 AM   #16
Senior Member
 
Capn Craig's Avatar
 
Join Date: Oct 2010
Posts: 408
God I love a happy ending!!!!! take all the advice in relation to what you paid for it and approach life with informed open eyes and you will prosper. To al the contributers bravo! you are the rock against which judge my my whako mind!
__________________

Capn Craig is offline   Reply With Quote
Reply

Thread Tools
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





All times are GMT -5. The time now is 05:26 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012