Go Back   Trawler Forum > Maintenance and Systems > Power Systems

Reply
 
Thread Tools Display Modes
 
Old 10-15-2016, 10:17 AM   #1
Senior Member
 
Dune's Avatar
 
City: Coastal SC
Country: USA
Vessel Model: Viking 65 CP MY (run at trawler speeds !)
Join Date: Jul 2015
Posts: 262
Potential reasons dinghy Yamaha 25 hp 4 stroke could be "weak" ?

With only 80 hours ? Starts instantly, idles smooth, both cylinders firing, recent (3 months ago) fuel filter change, recent addition of non ethanol fuel (estimate tank is probably a mixture of half gas that is 2 years old and half gas that is 1 month old) But even with just me (180 lbs) can't quite get it on plane (it= Avon RIB center console dinghy about 11 feet) Prop blades not perfect but almost so.

Ran fine before the hurricane last week, but now weak. Maybe hurricane action (it was loosely tied to floating dock) stirred up some gunk in tank and clogged newish fuel filter ? I don't like that theory however as it was weak from the get go after the hurricane....seems like if gunk stirred up it would take a few minutes to foul the filter....oh wait, come to think of it I did let it idle for probably ten minutes before I took off.

Does that sound plausable or something else to check ? Is tank gunk/algae an issue with gas tanks or only diesel ?
__________________
Advertisement

Dune is offline   Reply With Quote
Old 10-15-2016, 11:26 AM   #2
Guru
 
Crusty Chief's Avatar
 
City: Las Vegas/Portland
Country: USA
Vessel Name: Pairadice
Vessel Model: Selene 47
Join Date: Jul 2014
Posts: 600
I have a 25 Yammy on my dink and if the gas gets old it dosent run right. Suggest you drain the old gas, change the filter and put new gas in. I try to put stabil in as often as possible, but sometime forget. Good luck.
__________________

__________________
John & Tracey
Pairadice S4714
Mvpairadice.blogspot.com
" I can explain, but I can't make you understand"
Crusty Chief is offline   Reply With Quote
Old 10-15-2016, 11:35 AM   #3
Guru
 
mbevins's Avatar
 
City: Windsor
Country: Canada
Vessel Name: Keeper IV
Vessel Model: 44 Viking ACMY
Join Date: Nov 2013
Posts: 987
Have you checked to see if you have a bunch of water between the sole and hull? At 9#/gal doesn't take a to equal an extra body or two.
__________________
"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

mbevins is offline   Reply With Quote
Old 10-15-2016, 11:44 AM   #4
Senior Member
 
DHeckrotte's Avatar
 
City: Philadelphia, PA
Country: USA
Vessel Name: Revel
Vessel Model: 1984 Fu Hwa 39
Join Date: Nov 2015
Posts: 403
Doesn't take long for gas with ethanol, even with Stabil, to go bad. Been there this season with our Honda 15hp OB and our Honda eu2000i generator, and yearly with our 2hp Suzuki 2-stroke. A true PIA when you've done everything right. And a real PIA to clean up/out the mess.

Get the old gas out. Perhaps you'll have to disassemble the fuel pump, fuel filter, and carburetor and clean everything. Perhaps you'll get lucky and simply run the thing with clean gas. The Hondas do not like the remains of old fuel; the Suzuki could care less after it gets new fuel.

The Honda gurus in our marina swear by running the engine dry each use and using Seafoam treatment.

Given that one reason to own a Honda generator is for emergency use, how can one store gas? Pour the stored gas into the car and buy new each month? Yeah, that'll happen.
DHeckrotte is online now   Reply With Quote
Old 10-15-2016, 11:48 AM   #5
Senior Member
 
Donna's Avatar
 
City: Palm Coast
Country: United States
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 217
You may want to clean the carb and change the impeller. It worked for me.
Donna is offline   Reply With Quote
Old 10-15-2016, 12:40 PM   #6
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 12,082
For years I've been listening to talk like the above re 2 strokes as reason to get a 4 stroke. Eight strokes comm'in up?
__________________
Eric

North Western Washington State USA
Nomad Willy is online now   Reply With Quote
Old 10-15-2016, 04:39 PM   #7
Guru
 
jleonard's Avatar
 
Join Date: Jun 2008
Posts: 2,427
[QUOTE=DHeckrotte;488905

Given that one reason to own a Honda generator is for emergency use, how can one store gas? Pour the stored gas into the car and buy new each month? Yeah, that'll happen.[/QUOTE]
I don't have a Honda but I do rotate the lawnmower etc gas at my house. We've had ethanol for many years now and I just made a habit of rotating the gas about every 2 months. That plus I use stabil. Have not had a problem with any engine.
jleonard is online now   Reply With Quote
Old 10-15-2016, 06:20 PM   #8
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 8,565
Quote:
Originally Posted by jleonard View Post
I don't have a Honda but I do rotate the lawnmower etc gas at my house. We've had ethanol for many years now and I just made a habit of rotating the gas about every 2 months. That plus I use stabil. Have not had a problem with any engine.
We purchase ethanol free for our only gas powered Rib's or boats so don't have the issue. Interested in the discussion though in case we ever have to regularly buy with ethanol. We have had to for the Rib when cruising but burned through it always within a week.
BandB is offline   Reply With Quote
Old 10-15-2016, 06:22 PM   #9
Guru
 
djmarchand's Avatar
 
City: Essex, Ct
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,088
My bet is a plugged fuel filter. Years and years ago I had a 2 cycle dirt bike. All of a sudden it wouldn't get to full power. Out of the hole it was great, then a few seconds of accelerating later it would hit a wall.


Drained the tank, flushed out some sediment, replaced the little fuel filter (a joke compared to today's engines) and it ran like a champ.


David
djmarchand is online now   Reply With Quote
Old 10-15-2016, 06:29 PM   #10
Guru
 
C lectric's Avatar
 
City: Somewhere
Country: somewhere
Join Date: Oct 2007
Posts: 1,406
At the very least change the fuel filter. That will give you an answer. If it's ok then you are done , if not then look deeper.
I carry a spare filter under the cowling for that reason. Although the tank is clean, several years ago the filter clogged. I was just lucky I had that spare as we were several miles from the big boat.
C lectric is offline   Reply With Quote
Old 10-16-2016, 09:48 PM   #11
Senior Member
 
Datenight's Avatar
 
City: Noank, CT
Country: USA
Vessel Name: Datenight
Join Date: Jan 2008
Posts: 389
Dune,

I had an Achilles center console with a Yamaha 25 4 stroke that constantly leaked rainwater into the fuel tank until I redid the fuel fill and vent. Symptoms were the same. Could that be it?

Rob
__________________
North Pacific 39
Datenight is offline   Reply With Quote
Old 10-24-2016, 09:39 PM   #12
Guru
 
Pgitug's Avatar
 
City: Punta Gorda, fl
Country: Usa
Vessel Name: Escapade
Vessel Model: Nordic Tug 37 2002
Join Date: Jan 2015
Posts: 659
Replace the gas, ALWAYS add Stable, if that does not due it and the motor sounds like it is coming up to speed, check your prop to make sure it is not spinning on the resistance hub. Once they break away it's all down hill from there.
Pgitug is offline   Reply With Quote
Old 10-25-2016, 01:27 AM   #13
Veteran Member
 
nmuir's Avatar
 
City: West Vancouver
Country: Canada
Vessel Model: 50' Gulf Commander
Join Date: Feb 2013
Posts: 96
The larger Yamaha 4 strokes (40+hp) with carbs are legendary for carb problems. Some of the airways are tiny and get plugged with a whiff of sediment. As they are multi-carb setups going out of balance/synchronization causes all manners of issues too. It might be similar issues with the 25 hp units too - not sure. With mine (F50) I had to be festidious with carb cleaning and balancing. Once I purchased a manometer to do the balancing it became a lot more managable!
Good luck. If you are facing similar problems just going through the carb basics - whilst tedious - will see you done.
nmuir is offline   Reply With Quote
Old 10-25-2016, 11:29 AM   #14
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 2,769
Bottom growth??
Ski in NC is offline   Reply With Quote
Old 10-27-2016, 11:46 PM   #15
Veteran Member
 
City: PNW
Country: United States
Vessel Name: EXILE
Vessel Model: HANS CHRISTIAN TRAWLER
Join Date: Jan 2016
Posts: 97
I've experienced the problem described by Mbevens. My Caribe with double hull is a POS. Any water which enters the boat finds its way to the space between the hulls. Before you tear into the engine its worth an unplug to see if that could be the problem. I now have a transparent 5" inspection port which I watch closely and find Im often bailing water.
Good luck,-David
__________________

petdoc4u 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 08:26 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012