Can you diagnose a problem with an outboard?

[Tideline]

I have a two stroke 7.5 HP outboard. I had been using it quite happily for a short while, but was aware of the occassional "stutter" when it decided to miss and die whilst in high throttle. It restarted without problem but would not run in anything much more than a fast idle - give it some throttle and it just cut out.

I was not able to try anything dignostic at the time but have since had it running in a tank at home well warmed up, and rev'd up, without problem.

My thought was that it was something to do with the carburetter, or is that just too obvious?! Had plenty of petroil, and yes the tank was vented. So, petrol feed or carb problem?

 

[davidpbo]

Might be dirty fuel or a blocked jet. Are you using last years fuel by any chance?

 

[Lakesailor]

Main (running) jet is blocked.
Or you could have water in the float chamber.
Probably main jet.
Cleaning can be a pain in the neck as you can do it 2 or 3 times and then on the next occasion a bit of yellow gloop that's been hiding (where?) drops out.
Don't poke at it with anything harder than the jet material. You may enlarge the hole unwittingly. (arguments rage on this)
If using an airline, wear safety glasses.

 

[charles_reed]

Most probably a drop of water in the float chamber, blocks the needle-jet under high vacuum, but isn't effecting the idle jet.

Strip the carb, dry out thoroughly and see if that works.

You may have water in the tank, if so the problem will recur.

 

[VicS]

Agree possibly a dirty carb but don't dismiss an ignition fault. New plugs are always worth a try before tearing into other parts. Check latest recommendations for plug types and gap.

LS is right about not damaging carb jets by poking with anything that could damage them. I use soft copper wire when necessary

 

[absit_omen]

[ QUOTE ]
If using an airline, wear safety glasses.

[/ QUOTE ]

Do Ryanair charge for them - like earphones?

Anyway - outboard: 10 to 1 it is water in the fuel.

 

[Cliveshep]

There is also another fault that rarely occurs on those engines with timing controlled by the plate moved by the throttle linkage about the crankshaft axis which is the chafing of either the LT or HT wires by the continual movement. Worth a look at as this also gives engine running at one speed and cutting-out at another.