Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 15-03-2019, 02:11   #31
Registered User

Join Date: Oct 2012
Location: Noank CT. USA
Boat: Freedom 32
Posts: 129
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Not sure why these little motors are so temperamental. I have the Mercury 3.5 and have experienced the same problem. After a couple of attempts at cleaning and adjusting, I gave up and bought a new Tohatsu card from defender ($130) and it fired up straight away.
The lads in the boatyard say the problem is a result of "varnishing" from fuel left in the carb. So now I run the carb. dry when shutting off. It seems to help, but still not as reliable as my old two-stroke.
Craig Cape Town is offline   Reply With Quote
Old 15-03-2019, 04:50   #32
Registered User

Join Date: Jul 2016
Location: Anguilla
Boat: CheoyLee Offshore 33
Posts: 644
Images: 1
Send a message via Skype™ to masonc
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

I have a large gas powered tool collection as well as a number of outboards. Once I see problems, I buy a replacement carb. That fixes all the problems. You can't clean these small jets properly.
masonc is offline   Reply With Quote
Old 15-03-2019, 05:27   #33
Registered User

Join Date: Sep 2011
Location: Tarpon Springs fl
Boat: Morgan 384/ 1982
Posts: 378
Images: 3
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

I have the same engine, Had the same problem. The jets are TINY needle size the clog as the fuel eats the fuel line and the rubber flakes clog the jets. Clean the carb yes take it all apart clean the jets carbcleaner REPLACE all the fuel lines with the blue fuel lines that are ethonal proof .
I hated that engine and went cruising with it and had the carb apart 3 x a week for 3 months ! Till i learned the WHY !!!! Also dont go any where with out starting fluid just as a plan B !
stnick is offline   Reply With Quote
Old 15-03-2019, 13:21   #34
Now on the Dark Side: Stink Potter.
 
CSY Man's Avatar

Join Date: Aug 2003
Location: Palm Coast, Florida
Boat: Sea Hunt 234 Ultra
Posts: 3,962
Images: 124
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Quote:
Originally Posted by stnick View Post
I have the same engine, Had the same problem. The jets are TINY needle size the clog as the fuel eats the fuel line and the rubber flakes clog the jets. Clean the carb yes take it all apart clean the jets carbcleaner REPLACE all the fuel lines with the blue fuel lines that are ethonal proof .
I hated that engine and went cruising with it and had the carb apart 3 x a week for 3 months ! Till i learned the WHY !!!! Also dont go any where with out starting fluid just as a plan B !
If all the above problems are caused by ethanol in the fuel, then the solution would be no-corn fuel?
So far I have been using just that in my brand new 3.5, but still not easy to start. (I run the carb dry every time as well)
I thought perhaps a brand new motor has ininital internal friction that makes it harder to pull and start on the first try...?
At any rate, next time I will try the above trick on pulling slowly until the compression stroke is ready, and the above turning throttle beyond start position....Maybe there is a God and the thing will start on 1st or 2nd pull?
__________________
Life is sexually transmitted
CSY Man is offline   Reply With Quote
Old 23-03-2019, 07:58   #35
Registered User
 
dwedeking2's Avatar

Join Date: May 2014
Location: Key West, FL
Boat: Morgan Out Island 415
Posts: 911
Images: 1
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

So as a follow up.

I put a new carb on it ($120 at www.readysetboat.com and they shipped same day) and it starts right up w/ choke and just a tad above idle. After running 1/2 way out to the mothership I killed it. It started right up.

Might be psychological but it seems to be running smoother.

I'll see about consumption rate when i make the trip back in for breakfast tomorrow morning.

I also switch out the original prop (plastic 3x188x178mm) with an aluminum one (3x188x145mm) which seems to got me an additional 0.5mph (not important) and seems to power the hard dinghy easier.
__________________
S/V Pomaika'i Blog
dwedeking2 is offline   Reply With Quote
Old 23-03-2019, 14:16   #36
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Many plastic props don’t work as well cause the blades bend and reduce pitch.
SS props are “Better” than aluminum because the blades are thinner.

However it used to be thought that if you hit something real substantial like a rock, and aluminum prop would bust a blade, but the motor gears would survive, where an SS prop would bust the gears in the foot.

Keep your old carb, I still think you just have the float level set too high.
I’ve never yet seen a carb that I can’t successfully clean, although I have had to resort to an ultrasonic cleaner at times, which I did not bring with me on the boat.

I wonder why the Honda generators don’t seem to suffer the same carb problems?
a64pilot is offline   Reply With Quote
Old 24-03-2019, 04:46   #37
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,803
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

My guess is the same as post 11, too rich. His remedy or air restriction or exhaust restriction. Clue is no choke when cold & even harder to start when hot. Have you checked the plug colour?
I'm not too familiar with 4 stroke outboards ( sadly) but the principle should apply
Compass790 is offline   Reply With Quote
Old 24-03-2019, 04:55   #38
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,803
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Whoops didn't read last page& yr follow up before I posted. Glad you fixed it, most likely that A64 pilots diagnosis nailed it then.
My tip for little outboards is put a fuel line filter in if they don't have one & use a filter funnel as many others point out they have tiny jets & it doesn't take much to block them.
Compass790 is offline   Reply With Quote
Old 24-03-2019, 06:21   #39
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Bumping around the Caribbean
Boat: Valiant 40
Posts: 4,625
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

A lot of folks are recommending running the carb dry when done for a day or a few days. That is not a good idea and can lead to the very problems it’s intended to prevent. Only run the carb dry if you’re leaving the motor for an extended (three weeks or more) period. Better yet, run jet fuel through it and dry for extended storage.

If you run it dry frequently you’re actually concentrating water and varnishes in the carb because the fuel left in the carb will evaporate more quickly and leave water and deposits. Leaving the carb full leaves it full of solvent and less evaporation will take place.

I have a Yammie 2.5 hp four stroke and it’s never been run dry. It gets used 1-7 times a week but has sat in the locker for a couple of weeks now and then. Starts on first pull every time.
__________________
"Having a yacht is reason for being more cheerful than most." -Kurt Vonnegut
Suijin is offline   Reply With Quote
Old 24-03-2019, 06:31   #40
Registered User

Join Date: May 2018
Location: Northfield, NJ
Boat: Hunter 170
Posts: 85
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Buying a new carb is kind of silly to me.

My brother is a very experience mechanic and the trick to cleaning the small jets is wire.

I have a selection of spring steel wire of small and very small diameters. The jets get reduced in size due to residue that gets left behind. Usually this is poor start and idle, but then people compensate by opening up the carb some.

So using a wire you kind of polish out the the residue keeping it damp with 2+2 carb cleaner. The wire will not open up the jet so long as you are not too aggressive.

I got a little 50cc motor cycle running again after the carb likely sat with water in it for a year or more. I was just careful and worked all the passages.
ShoreFun is offline   Reply With Quote
Old 24-03-2019, 09:09   #41
Registered User
 
dwedeking2's Avatar

Join Date: May 2014
Location: Key West, FL
Boat: Morgan Out Island 415
Posts: 911
Images: 1
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

The fuel consumption is back to normal.

I'll try to clean the old carb and adjust the float. Then I'll have a backup.

With my hectic work schedule I don't have time during the week to play with these issues so being able to just swap out carbs then doing a good cleaning at my convience
__________________
S/V Pomaika'i Blog
dwedeking2 is offline   Reply With Quote
Old 24-03-2019, 10:07   #42
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Re: Tohatsu 3.5 HP - Hard To Start / Fuel Economy

Quote:
Originally Posted by dwedeking2 View Post
The fuel consumption is back to normal.

I'll try to clean the old carb and adjust the float. Then I'll have a backup.

With my hectic work schedule I don't have time during the week to play with these issues so being able to just swap out carbs then doing a good cleaning at my convience


A lot of people do that. Look into a cheap ultrasonic cleaner, it can clean jewelry and other things too, just be careful about which jewelry, I think it will shatter opals for instance.
Stiff monofilament leader is good to clean out jets, it’s stiff so it works, and it’s plastic so it won’t bore out a brass jet.
Just don’t use an acetylene torch cleaner as I have seen some do, because it will definitely act like a jet drill and change the jet size.
a64pilot is offline   Reply With Quote
Reply

Tags
fuel

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tohatsu 5 2-stroke VS Tohatsu 6 4-stroke Distant Shores Auxiliary Equipment & Dinghy 33 13-04-2015 19:16
Perkins 6.354 Diesel Engine Fuel Economy konazihua Powered Boats 19 14-05-2014 13:50
Fuel Consumption and Fuel Economy Seif Powered Boats 11 18-10-2012 08:35
Another Fuel Economy Question Tony B Powered Boats 10 20-07-2011 02:33
Fuel Economy sailorboy1 Engines and Propulsion Systems 6 16-02-2010 04:47

Advertise Here


All times are GMT -7. The time now is 19:14.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.