Reply
 
Thread Tools Search this Thread
 
Old 24 November 2018, 02:32   #1
Member
 
Country: UK - England
Town: kingswinford
Make: self built aluminium
Length: 8m +
Engine: Yamaha 420 ste
Join Date: Jun 2002
Posts: 14
Yamaha 421 STI

Anyone know how to fix a Yam 421 revving to maximum while in neutral
As soon as it starts, revs quickly increase until I turn it off on the key
Rev counter appears to have stopped working simultaneously
Any advice appreciated

Thanks
Andy
__________________

__________________
AndyMicklewrigh is offline   Reply With Quote
Old 24 November 2018, 04:09   #2
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 1,995
Have you checked the throttle leaver on the pump isnt stuck?
__________________

__________________
beamishken is offline   Reply With Quote
Old 24 November 2018, 05:47   #3
RIBnet supporter
 
Brian's Avatar
 
Country: UK - Isle of Man
Town: Peel, IOM
Length: no boat
Join Date: Nov 2000
Posts: 2,385
RIBase
Not had this particular problem, Andy, but......
if the throttle was open wide when you switched off, maybe it has now snapped/broken? thus leaving the engine in full go mode when you restart.
__________________
Brian

"Ribbing-the most expensive way of travelling third class"
Brian is offline   Reply With Quote
Old 24 November 2018, 06:44   #4
Member
 
Country: UK - England
Town: kingswinford
Make: self built aluminium
Length: 8m +
Engine: Yamaha 420 ste
Join Date: Jun 2002
Posts: 14
Cable is ok
Throttle mechanism appears to work fine
Seems like something inside the main pump is stuck in the wide open position
I must have done thousands of miles on this type of engine/ pump with no problems before
Just limped round from BRIXHAM to Dartmouth on one engine in F5-7 but itís in the river now ready to be lifted for the winter
Annoying thing is I canít get max revs when I want to
LOL
__________________
AndyMicklewrigh is offline   Reply With Quote
Old 24 November 2018, 07:40   #5
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 1,995
Sounds like time to take the pump off not much else will give you full rpm and allow you to still switch off. so more than likely an internal pump fault
Fortunately the pump is relatively easy to get out assuming you have access in the engine bay
__________________
beamishken is offline   Reply With Quote
Old 25 November 2018, 15:44   #6
Member
 
redrubber xl's Avatar
 
Join Date: Jan 2012
Posts: 2
Itís the pump I had same problem with my 422 thy donít like low sulphur diesel you need to put oil it .
__________________

__________________
redrubber xl is offline   Reply With Quote
Reply

Tags
yamaha

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 01:38.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.