Help! Mercury 2 stroke Outboard playing up.
Ok, ok - its a Mercury (it was on the boat when I bought it). 1991, 90 HP, 2 stroke, had rebuild and service a few months ago.
So, I'm coming back in today and the trottle starts playing up - it doesn't want to stay at one speed - it groans its arse off then builds up momentum then wants to go full tit. So I'm spending forever speeding up and slowing down, looking like a knob. After doing that for a while, it doesn't want to rev up at all - will only go dead slow and if I try to speed it up it coughs and splutters and wants to die. So I pull up and fish for a bit - turn it off for half an hour. After that I start it back up and its right as rain..... for a while, then the whole process starts all over again....
I checked throttle friction, linkages, fuel - apart from that I don't know much about outboards. When I washed it down later I noticed there was some fishing line wrapped up in the prop - so I've got a job to do tmw... but it doesn't really seem like that'd be enough to cause that much drama...
My knowledge of car engines is suggesting a fuel delivery issue, blocked fuel filter or something.
Any ideas....?
The Black Baron
strike_zone
Posts: 403
Date Joined: 09/09/10
carbys
you may need to re-kit your carbys
OLD BANGA
Posts: 267
Date Joined: 02/04/10
Outboard - fuel tank
Just a long shot, but have you checked the breather on the fuel tank, sounds a little bit like the motor is starving for fuel when the vacuum builds up in the fuel tank. I too have a 90 Merc about the same vintage, check the simple things first.
Cheers,
Old Banga!
OLD BANGA
TGMitchell
Posts: 221
Date Joined: 24/11/09
cool - will try that
cool - will try that
The Black Baron
iana
Posts: 652
Date Joined: 21/09/09
Roger that "Old Banger"
Roger that "Old Banger" sounds like a fuel issue. What kind of fuel tank, portable or in built?
Could be staving because of a vacuum, breather, could be air getting in the line, conections, or could be blocked fuel filters and or a fuel pump on the way out.
Start at the beginning of the fuel system and work through it.
TGMitchell
Posts: 221
Date Joined: 24/11/09
cheers guys
Thanks - took at quick look - taking it back to the dealer, still under warranty.... but I'll keep it in mind if it happens again....
The Black Baron
poida
Posts: 234
Date Joined: 08/08/05
running on one cylinder
Sounds like it could be running on one cylinder, with the 2nd cylinder cutting in and out.
Good job its under warrenty
scuttlebutt
Posts: 454
Date Joined: 24/03/06
Check fuel lines. The
Check fuel lines. The genuine Merc silver coloured fuel lines are notorious for having the insides collapse in hot conditions. I had this happen on my last motor (90 Optimax). The inner membrane of the genuine fuel line collapses causing a blockage.