Sneezing at idle when starting after 30 min pause

[Andrik]

I have an odd idle-problem with my 150 98`Ocean Pro. It starts and runs very well at idle and full speed when motor is cold. When hot, it also starts and runs good at idle and full speed. BUT; When motor have been shut off for 30 min, it is impossible to run well at idle. It starts, sneezes and stops after a little while. When increasing the RPM and revving the motor some times, getting some "heavy" circulation, it will as usual run well again at idle. If I then stop it and start it again, it will run well (but if I wait for another 30 min... - it will sneeze and not be very cooperate)

I have changed plugs, and tried another power pack. There are no problems at full speed.

PROBLEM: Why does it run good at idle when cold and warm, but not when it is has been warm and have started getting colder?

 

[boobie]

Try hitting the choke when it acts up.

 

[Andrik]

Thanks,I`m not exactly sure of what you mean - do you mean pressing the primer after firing it up?

 

[interalian]

Yes. The motor is half cool when you restart after 30 minutes. Sneeze is a lean condition, and pressing the primer button will richen the mixture.

 

[Andrik]

Thanks, I tried pushing the primer after firing up the motor (after 30 minutes). If I push more than 1/3 sec, I kill the motor, but if just push 1/3 sec when I hear it will start to sneeze, I keep it going. But I have to be alert and do this many times. Is this right?

 

[interalian]

I'd treat a re-start after 30 minutes more like cold start - raise the idle lever about half way and crank it up without primer. If it stumbles/sneezes, a couple of quick dabs on the primer is all you need.

 

[Andrik]

The problem is that I have to do this a lot of times to make it work well at idle again...

 

[Bosunsmate]

Well if pressng the choke in keeps it going then i suggest a carb clean

 

[JDusza]

You've got a fuel delivery problem and the engine is starving. Sneezes usually indicates running on the edge of too lean.
J

 

[Andrik]

But why does it run good at idle when cold and warm, but not when it is has been warm and have started getting colder? Can I adjust the carbs to manage this?

 

[JDusza]

Sticky needle valves inside the carburetor may cause this. And, just to be sure clean the fuel filter.
You've got three carburetors. I highly suspect a sticky valve because one carburetor can "go dry" with a stuck valve. Fuel seeps in after a brief rest but then gets used up at acceleration, high speed running. Try squeezing the fuel ball to force fuel into carburetor when this happens. Much like using the choke as mentioned above, but perhaps a little more forceful (?).
Clean and rebuild the carburetors.
to test float valve, hold the carburetor upright and blow into the fuel inlet valve. Your breath should flow into the carburetor. Flip the carburetor upside down, closing the valve, repeat the blow and you should feel strong resistance.
Time will reveal the relation to temperature cycling, Let's get her useful again.
J

 

[tomhath]

I think your motor has what OMC calls "Quickstart" - it advances the ignition timing after a cold start to make it idle better, then goes into normal operation after several seconds for running.

It sounds like your engine works as designed when cold and isn't needed when hot, but isn't engaging Quickstart when the engine is warm. That might indicate the engine is due for a tune-up.

 

[racerone]

Facts.---A model number should be posted to figure out how many carburetors there are on this thing !-----What is the water temperature in the boating area ?---Reason is --The motor may be " warm " but as soon as you start it the motor fills up with perhaps very cold water and needs to warm up all over again !!

 

[Andrik]

Its a V6 ocean pro, six carbs. I don`t think this is a carb problem, since the problem has to do with the temperature of the motor. Anyway, i overhauled the carbs last year. The temperature of the water is generally between 60 and 70 Fahrenheit.

I guess the quickstart as suggested by Tomath could be a track. But I do not know how to check this.