Engine Problems!

[andreworiordan]

Got a 40hp Mariner XRNLI (2004) the engine is running fine, when i start it up its perfect but as soon as i put into gear she runs for a min but when i power up she dies off, i cant get full trottle..its like the engine is stopping itself from running at full trottle...well anything over tick-over speed. i first thought it may be fuel problem but the fuel appears to be ok, then i thought spark plug problems but the appear to be ok....anyone know what it may be...im going to get it serviced on wednesday but im trying find out what is going on....thanks guys!

[PeterR]

Have you undone the breather screw on the tank

[Pete7]

Blocked jets in the carbs or reeds stuck because the fuel has evaporated and left a sticky varnish substance behind. Let the dealer sort it out.

Pete

[PeterR]

Could easily be fuel starvation

[andreworiordan]

when the engine is in idle, it will run all day, its only when you put it in gear and give it power. sometimes it runs fine but for the most part it dies and you must bring it back to idle, only have the engine on the boat 2days and only been out a few hours yesterday and today. thought it might be sparkplugs because it started todie, i took off the cover and ratteled the plugs, she ran fine for like 5min and then started to die again.

[PeterR]

I seem to remember the timeing advances on the fly wheel when you accelerate maybe this has come adrift.Two strokes are very simple so should be easily sorted out.As long as you have trust in your dealer.But it is good to have an idea yourself

[codprawn]

I also think it's fuel starvation - either a blocked breather or filter.

[Tim M]

I had a similar problems with a 1998 Mariner 40 2 stroke. It turned out to be blocked jets - as Pete says. Quite a simple job to sort out.

[andreworiordan]

...how hard are these to clear? am i better off getting a service or is it possible to do it myself, are there other tell tales of blocked jets that might confirm they are blocked?

[Nos4r2]

If you're not sure what you're doing with it, take it to the dealer. If you separate the carbs and mess up the synch it won't run right. It's probably minor but if you do it wrong it'll cost you more to pay someone to sort a mistake... and yes, it sounds like blocked jets or sticky reeds. Could also be water in the carbs.

[Bigmuz7]

I had a 135 that did this.. mixture was too lean in my case, and wouldnt throttle up pulling a load (such as a skier), but idled and ran otherwise fine, but I agree.. good advice.. have your dealer check it for you

[Jimmy C]

I had a mariner 40 that did exactly the same thing and it was a combination of pretty much everything mentioned above!
To start with I took off the carbs, gave them a good clean out to get rid of all the sediment left in the fuel bowls, then replaced them, then when it was running tweaked the mixture screws, that really sorted it out. Once it was running well then gave a squirt of the carb cleaner.

It sounded beautiful after that!

Recommed starting with mixture screws tho!

Jimmy

[9D280]

Same story with a Suz 25....

The way to check your idle mix is (and only do this afloat - it's pointless on muffs or in a bucket) As you accelerate, prod the choke button for a moment (or out / in with the pull thing on the engine if you are on tiller). If it gets you going (will seem like you hit a Niotrous button) it will probably then run quite happily at open throttle, as your main jet will have kicked in by then.

Then its a simple turn of an adjuster screw(s) on the carb(s), but don't fiddle unless you know which one to turn otherwise youll mess something else up. Someone on here can probnably elaborate on the particular screw......

[Richard Selman]

My yamaha 50HP 2-strokes start to experience problems like that if I don't drain the carbs every 4 months or so. Takes 2 minutes to check.

Richard

[andreworiordan]

How do I drain the Carbs? what do i need to do?

[ashbypower]

You should always drain the Carbs after use if the engine is not going to be used for a day or two. The best way is to disconnect the engine fuel line whilst it is running. The engine will then just die when fuel has gone. Best time to do it is whilst flushing out with fresh water. I take it that you do flush the egine after use,

[andreworiordan]

Do you think by flushing the Carb it might fix the problem?

[ashbypower]

No No No!! by flushing I mean flushing the coolant water jacket with fresh water to rid it of salt!!

[andreworiordan]

...so draining the Carbs, might that fix it?

[Tim M]

I would think you'd need to take the carbs off and give them a good cleaning out - theres probably some crap in there. You'll need a set of spanners, and a service manual. It's not a difficult job.
Alternatively take it to an outboard engineer.