mariner 15hp problems please help

[jono_uk]

i have just purchased a 15hp mariner what is about 1985 age 1 month ago and have just got round to fitting it onto my boat it starts 1st pull but sounds like it only running on one cylinder i took it out and with wot there is no power and it tends to stall if i go from wot to idle this only happens under load. i checked the plugs the top plug was wet and the 2nd plug was a little fouled up i cleaned the pulgs and tried again but still the same it doesnt want to rev up.. what i did notice if i hold it wot whils going p river the engine tends to start revving up and down on its own i would be very gratefull anyone got any ideas as i meant to be going away in it in a couple of weeks

ps i have checked and both of the plugs seem to be sparking ok
Also does anyone know what plugs are meant to be in this engine it hasnt got a serial number but is def around the 1985 mark in age

 

[jono_uk]

Re: mariner 15hp problems please help

please help as taking boat down river soon to go to a rally and not got long to sort out

 

[trussmonkey]

Re: mariner 15hp problems please help

how long did it sit?
how did it run when, you got it a month ago?
what have you done with this motor?
did you try to pump the primmer bulb while it was running?

more info = more help!

 

[MaggieRose]

Re: mariner 15hp problems please help

Have you taken a look inside the carberator. Dirty carb will give the problem you mentioned, and cleaning a carb is a cheap and easy fix.

 

[jono_uk]

Re: mariner 15hp problems please help

how long did it sit?
how did it run when, you got it a month ago?
what have you done with this motor?
did you try to pump the primmer bulb while it was running?

more info = more help!

only started it a month ago in a bucket when i picked the engine up it starts on the 1st pull all ive done is fitted onto my boat went to run it it starts fine and soon as you open throttle up whilst moving it starts missfiring and trys to cut out the bottom plug keeps oiling up and the top plug seems ok both seem to be sparking i tried the primer bulb whilst running and it does not make no difference when it in gear and throttle open it starts picking revs up then drops then picks up again then drops and keeps repeating

 

[jono_uk]

Re: mariner 15hp problems please help

UPDATE......... removed air filter and seems to run ok under load and at wot the plug what was fouling up is staying clean now has anyone had a similar problem before as i am going 40 miles down river soon and want this engine to be reliable as possible....thanks

 

[Don S]

Re: mariner 15hp problems please help

removed air filter and seems to run ok

Outboards don't have "Air Filters". Can you post a picture of this? Somehow I think the previous owner may have tried to do something that shouldn't be done.

 

[jono_uk]

Re: mariner 15hp problems please help

Outboards don't have "Air Filters". Can you post a picture of this? Somehow I think the previous owner may have tried to do something that shouldn't be done.

as you can see above where the air filter is situated or is this meant to be just a air box with no filter inside?? this isnt my engine its a pic i found which is a similar model....Also my dad has a 2006 suzuki df25 v twin and that has a air filter box fitted as standard but i never had it off so not sure if theres a element behind it?