Reply
 
Thread Tools Search this Thread
 
Old 20 May 2008, 14:29   #1
Member
 
Country: Other
Town: Torre Pacheco,Spain
Boat name: Seabiscuit
Make: Sabinal 190
Length: 6m +
Engine: Outboard
Join Date: May 2008
Posts: 1
Yamaha outboard engine running poor

Hi,
I have a 19 year old Yamaha 140,V4 ,1.7 ltr.Autolube,outboard.It runs reasonably well when ideling up to 2000 rpm but inbetween 2000 & 6000 it runs slugish & jumps from 6000 to 2.5.Sometimes it will all of a sudden run right up to the max. of 7000 rpm & stays there, running perfectly until I take it back down again,all with the idle throttle of course.I've tried to run it at sea & it cruises fine up to 2-2.5 rpm but anything higher than that it dies a death.
I've cleaned both carbs,replacing the rubber rings ion the jets,sprayed plenty of carb cleaner in there,checked the fuel,oil,petrol filter ect.,new plugs.The oil sensor is faulty (overflows if stays connected at the tank) but I've tried disconecting it at the engine & there is no difference,so it's not the low oil level engine cut-out.Sometimes it will go to max. revs. on it's own & won't switch off with the key or by pulling the cut-out cord,it only goes back to normal when I switch on the choke switch next to the throttle.
Any suggestions for a cure are very welcome please.

All the best
Steve.
__________________

__________________
bolger is offline   Reply With Quote
Old 20 May 2008, 16:32   #2
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
Length: 7m +
Engine: Opti 225/Yam 85
MMSI: 235090687/235055163
Join Date: Jul 2005
Posts: 12,645
RIBase
Quote:
Originally Posted by bolger View Post
Hi,
I have a 19 year old Yamaha 140,V4 ,1.7 ltr.Autolube,outboard.It runs reasonably well when ideling up to 2000 rpm but inbetween 2000 & 6000 it runs slugish & jumps from 6000 to 2.5.Sometimes it will all of a sudden run right up to the max. of 7000 rpm & stays there, running perfectly until I take it back down again,all with the idle throttle of course.I've tried to run it at sea & it cruises fine up to 2-2.5 rpm but anything higher than that it dies a death.
I've cleaned both carbs,replacing the rubber rings ion the jets,sprayed plenty of carb cleaner in there,checked the fuel,oil,petrol filter ect.,new plugs.The oil sensor is faulty (overflows if stays connected at the tank) but I've tried disconecting it at the engine & there is no difference,so it's not the low oil level engine cut-out.Sometimes it will go to max. revs. on it's own & won't switch off with the key or by pulling the cut-out cord,it only goes back to normal when I switch on the choke switch next to the throttle.
Any suggestions for a cure are very welcome please.

All the best
Steve.

Not what you'll want to hear but it sounds like you've got more than one problem there so very hard to diagnose. Take it to a dealer. It needs workshop facilities.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 21 May 2008, 14:10   #3
Member
 
Country: UK - England
Town: Exmouth, Devon
Length: no boat
Join Date: Oct 2004
Posts: 765
Could be the CDI - some of those symptoms are very similar to the ones I had on a Yam 115 V6 and that was the cause.
__________________
www.allgadgets.co.uk
Tel 01395 227727
MikeCC is offline   Reply With Quote
Old 22 May 2008, 07:30   #4
Member
 
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,611
Quote:
Originally Posted by bolger View Post
Hi,
when ideling up to 2000 rpm but inbetween 2000 & 6000 it runs slugish & jumps from 6000 to 2.5.Sometimes it will all of a sudden run right up to the max. of 7000 rpm & stays there, running perfectly until I take it back down again,all with the idle throttle of course.
Steve.
DON'T run in neutral at that speed or you'll be adding to your problems......

Sounds electrical if it jumps. I had a similar thing on mine at load that got progressivley worse, then found one of the spark plugs was well on its way to being short circuit. (Megger proved that). Mine's 2 cyl and so it was quite obvious what was happening as one was cutting in & out like it was on a random switch. Pulsing high voltage does some funny things with semi short circuits, and spark plugs don't last forever......

I'd check & clean all the electrical connections in the engine first - it's amazing what 20 years of salt air can do to a bullet connector. If that doesn't cure it then change the plugs, it should be a cheap test. If that doesn't work, I'll echo NoS' comment & say go to a dealer.

Incidentally, does it do the same afloat and under load? (i.e. in gear)
__________________
9D280 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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 14:09.


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