Reply
 
Thread Tools Search this Thread
 
Old 19 July 2015, 05:20   #1
Member
 
Country: Ireland
Town: Dublin
Boat name: Augusta
Make: Zarco
Length: 5m +
Engine: outboard, petrol, 50
Join Date: Mar 2014
Posts: 10
Tohatsu 2 stroke 50hp cuts out at high revs

Hi, I have recently purchased a RIB and I am new to boating!
I changed the spark plug(3) on the outboard a couple of months ago and checked the fuel and oil filters. Since them the engine cuts out at high revs. I starts back up immediately and runs fine on half revs, I am thinking that fuel isnt getting through but I am not sure what to check, any help greatly appreciated.
__________________

__________________
pabeer is offline   Reply With Quote
Old 19 July 2015, 05:47   #2
Member
 
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 708
Stating the obvious, but start at the fuel tank - pickup pipe, vent - & work your way all the way through.
Is the fuel filter blocked?
If it didn't do this before you worked on it then the first thought is that something you've done/replaced is the problem.
__________________

__________________
paintman is offline   Reply With Quote
Old 19 July 2015, 06:35   #3
Member
 
Country: Ireland
Town: Dublin
Boat name: Augusta
Make: Zarco
Length: 5m +
Engine: outboard, petrol, 50
Join Date: Mar 2014
Posts: 10
Thanks Paintman, my boat is down in Portugal and I will be going down at the end of July so I will check then. I had a couple of people 'helping' me when I was working on it and it could be that something was put back incorrectly. I will check the fuel filters first!
__________________
pabeer is offline   Reply With Quote
Old 19 July 2015, 07:02   #4
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,270
RIBase
Is it definitely the right sparkplugs? Tohatsu 50hp model D2 uses NGK-BH8S-10 or BR8S-10 gapped at 1.0mm. Ensure the HT leads sit tight on the plugs. Sometimes you can crimp the connection if it's a little suspect.

Definitely rule out fuel as suggested. The male fuel connector can fail. The push-pull release is prone to corrosion, so lube lightly after cleaning with steel wool. Also check the 'o'-ring and ball-bearring inside hasn't been dislodged.

When did you last replace the primer bulb? The fuel bulb internals can collapse, so if it feels particularly hard or is difficult to prime, then replace. Genuine Tohatsu or Quicksilver only.

Drain the carbs using the large slot hex nut on each carb bowl. Any contamination, then strip the carbs down and clean. Don't adjust pilot screws, etc.

Finally, the fuel pump. With the engine running, you can detach slightly from the engine. The engine produces a vacuum which draws fuel. You can test by pressing the fuel bulb to see fuel flowing out. if it's suspect, then opt for a new diaphragm kit and rebuild. New fuel pumps are daft money.

Because the boat is abroad, I'd order a new fuel-pump kit, primer bulb, fuel hose connector and spark-plugs. All useful spares anyway. You don't want your trip ruined because you're waiting on parts. Not sure what dealer network is like in Portugal. When I was there last it seemed like shiny Yamaha 4-strokes all the way.
__________________
Is that with or without VAT?
spartacus is offline   Reply With Quote
Old 19 July 2015, 07:52   #5
Member
 
Country: Ireland
Town: Dublin
Boat name: Augusta
Make: Zarco
Length: 5m +
Engine: outboard, petrol, 50
Join Date: Mar 2014
Posts: 10
Hi Spartacus, Thanks very much for all that information, its very much appreciated. Could you recommend and online store where I could order the items you mentioned?
__________________
pabeer is offline   Reply With Quote
Old 19 July 2015, 08:01   #6
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,270
RIBase
I order from Gaelforce (Inverness), ask for Nik. Call and he'll locate part numbers, etc. Tohatsu UK have 5 shipping charge even if it's a single rubber grommet so it makes sense to order a few things at the same time. Gaelforce then forward onto you, plus VAT and postage.

Chandlery, Sailing Clothing & Boat Electronics | Gael Force Marine
__________________
Is that with or without VAT?
spartacus is offline   Reply With Quote
Old 26 July 2015, 02:56   #7
Spammer
 
Country: Canada
Town: Southern Ontario
Boat name: -Unknown-
Make: SeaMax
Length: 4m +
Engine: Merc/Minn Kota
Join Date: Mar 2012
Posts: 216
Hi, Plug Gap wrong; High tension wires leaking; Coil is where I'd start looking. You may also check each plug for fowling indicating misfiring which would most certainly point toward one or more of the above. Good luck.
__________________
Nightfisher is offline   Reply With Quote
Old 01 August 2015, 02:42   #8
Member
 
Country: Ireland
Town: Dublin
Boat name: Augusta
Make: Zarco
Length: 5m +
Engine: outboard, petrol, 50
Join Date: Mar 2014
Posts: 10
Thanks Nightfisher, I am in Portugal now and will check all suggestions. I suspect that it could be the spark plug gap as the problem only started after I changed the plugs and I didn't check the gap before I put them in!
__________________
pabeer is offline   Reply With Quote
Old 01 August 2015, 05:25   #9
Member
 
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 708
If it doesn't solve it & you still have the old plugs be worth putting them back in to check.
__________________
paintman is offline   Reply With Quote
Old 03 August 2015, 02:58   #10
Member
 
Country: Ireland
Town: Dublin
Boat name: Augusta
Make: Zarco
Length: 5m +
Engine: outboard, petrol, 50
Join Date: Mar 2014
Posts: 10
Plug gaps and cleaning fuel tank breather seems to have fixed the problem, thanks to everyone for their help. Problem now is an intermittent engine alarm with no associated oil light! I took the oil filter off and I think air got in then, anyone know of an easy way to purge the oil lines? Thanks again guys!
__________________

__________________
pabeer is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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


» Member's RIBs

Azul

Azul

Osprey

tocho
Add your RIB



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 02:39.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.