motor help please
Submitted by aalfred on Sat, 2010-08-21 16:36
Hey guys, been a member for a while but havent posted much. Got a question about a motor problem on my 40hp mariner so thought id see if anyone had any advice please?
At high revs the motor seems to suffer fuel starvation and begins to cough after running smoothly at lower revs. I have already replaced the fuel tank, fuel line and fuel filter and have also emptied the carbie. The previous tank had water contamination which i though had caused the problems, but now after doing everything i can think of, the problem remains when running the motor at high revs.
Any advice would be greatly appreciated, cuz im all out of ideas.
cheers
Dale
Posts: 7930
Date Joined: 13/09/05
I'd be looking at the
I'd be looking at the secondary injectors on the carbies, one sounds like one may be blocked.
Cheers
Dale
"Just because you are a Character, Doesn't mean you have Character."
Mr Wolf
iana
Posts: 652
Date Joined: 21/09/09
A story
When I purchased my first boat with a newish 70Hp suzi on it, I would head out everything being fine. Opening up, at about 3200 rpm it would behave as though someone pulled back the trottle.
RPM below that and it was fine. Asked various outboard motor gurus, defianly a fuel problem. I replaced fuel filters, fuel tank, and stripped the motor down to the balance tank but everything was fine.
Asked the Gurus again, it must be a sensor problem, got the guys in with their laptops and the prognosses was all sensors are fine. So went to buy some sparkplugs and again explained the problem, not sparkplugs definately fuel.
OK to hell with the guru's, the only time this problem occurs is under load and at 3200 RPM and above. Lunched the boat and tied it to the jetty. Wound the RPM up till the problem occured and pulled off spark plug leads.
Yep one F------n spark plug was the problem. replaced that and all was sweet.
ledge64
Posts: 1029
Date Joined: 24/11/09
Had a mate who had a simular
Had a mate who had a simular problem and went through the same execises with the gurus turned out to be the diaphram in the carby had a split and could only be seen at high revs hope this helps
grayzeee
Posts: 2283
Date Joined: 09/07/09
the breather to the fuel
the breather to the fuel tank isn't blocked??
If I spent half as long fishing , as I do reading this bloody forum , I'd be twice the fisherman I am.
aalfred
Posts: 669
Date Joined: 13/06/09
Hi Guys, thanks for all the
Hi Guys,
thanks for all the tips. For graham the fueltank breather was open, but the primer seems to get soft quickly, dont know if that has anyting to say( cuz i'm new to boating). I certenly will put in some new sparkplugs and try that.
Cheers
Faulkner Family
Posts: 18085
Date Joined: 11/03/08
as Grayzeee saidsounds like
as Grayzeee saidsounds like there seems to be an air blockage, maybe check all air lines . had an outboard do that years ago
RUSS and SANDY. A family that fishes together stays together
PJAY
Posts: 1005
Date Joined: 12/05/09
try a different fuel line
try a different fuel line and connector...
The Kimberley....perfect one day and more perfect the next!!!
Auslobster
Posts: 1901
Date Joined: 03/05/08
Spark plug leads.
Had exact same prob with 40hp Yammie. Replaced the plugs, still missing at higher revs. Replaced the leads, problem solved. Of course, since it was an older motor, and since this is WA (Wait Awhile) it took over a week to get the new leads in the first place!