Engine cutting out- throttle?

[n428]

Yam 50 4stroke- serviced about 30 hours ago.

A couple of times in the last outing the engine cut out as I went from low displacement speed and tried to accelerate (by pushing throttle). Engine cuts out quietly- no obvious noise. Fuel related issue? Plenty of fuel in tank and fuel bulb remains fairly firm?

Any ideas? Many thanks

[Polwart]

cuts out as in stalls (and needs the key to restart) or cuts out as in the revs drop away but it keeps running ?

[neil.mccrirrick]

Timing problem, is the engine flooding, too much fuel?

[n428]

Sorry for confusion.

Cuts out totally. Need to use key to restart the engine.

Thanks for advice so far

[Polwart]

Originally Posted by n428

Sorry for confusion.

Cuts out totally. Need to use key to restart the engine.

Thanks for advice so far

mmm.... thats what I thought you meant - I'm out then!

[sam12345]

Sounds like what i call a flat spot, but the engine cutting out completely is the weird thing.
The most common problems of throttle/power related problems are:
Fuel... stale, not getting through.
Carbs... gaskets gone, not syncd.
Coils gone

Does the engine literally just die, or does it pick up revs then die, or bubble a bit and die.

[n428]

Engine just dies. Doesnt happen every time I accelerate to get the boat on the plane- just intermitently.

[biffer]

sounds like electric's' if it was fuel it would die more slowly, have a look at kill cord or wiring loom for anything loose

[Nos4r2]

Originally Posted by biffer

sounds like electric's' if it was fuel it would die more slowly, have a look at kill cord or wiring loom for anything loose

I agree. Exactly which bit of electrics is a bit harder.

Either that or the end of your killcord is worn. I've had that happen-engine cuts out because it doesn't pull the killswitch out far enough.

[alystra]

Isn't this just a case of flooding by opening the throttle too quickly from slow speed?

If I slam the throttle wide open from just above tickover in gear, my engine stops, instantly - but if I quickly ease the lever back it picks up again or the spinning prop starts it and we carry on. If I'm not quick I have to use the key. After 2000 RPM the problem goes away.

This behaviour is exactly similar to that of my first few cars. Basically the throttle pumps extra fuel into the engine and puts out the fire. Push the accelerator down gradually to get maximum acceleration. That's what we were taught, and it worked. Stamp on the thing and the engine coughed and spluttered. That was with just two carbs. My Merc has four.

Of course, if your engine is a modern fuel injected, computerised one then you may have to pay someone a fortune to plug in a lap top and come to the same conclusion.