Engine stops after 4-6 seconds

[ahe]

Recently my M20A seems to have a problem shortly after starting. 

 

It starts without problems, but after 4-6 seconds the RPM's lowers and the engine stops. When i start the engine again it  starts without problems, but runs a little low rpm before it begins to run smooth. The engine is running fine after that. 

 

The engine is standard O-360 carb without primer. It is primed by the throttle 2-4 times push/pull before starting. 

 

It recently got out of 100h service and the spark plugs and everything else looked fine. My mechanic thought the start problems were just because of the winter and freezing  temperatures, but i am not convinced - i don't remember this behavior from the last winters.

 

I suspect the acceration pump, it is used to prime the engine with the throttle, and if it does't work 100% the engine would not get primed corretly - but would it even start the first time then? 

 

Any other suggestions, or am i just overly cautious and it is just the winter?

 

Best regards

[carusoam]

What part of the world are you in, and what's the OAT?

How many throttle pumps at this temperature does it usually take to start?

The O360 Would use 10 pumps a temps below freezing and a few attempts to start.

Do you use pre heat?

Is your battery strong enough for this effort?

Fuel pump on?

These are a few considerations for this time of year from my C experience.

Bet regards,

-a-

[omega708]

I'll chime in that on my O-360 (67 C model) if the temps are near or below freezing I have to pump the throttle ~ 10 times, as indicated by carusoam, for a healthy and easy start.

[ahe]

Europe, Denmark - currently the temperatures is -5 to +5 celcius. I normally prime it 4 times during the winter, 2 during the summer. I do not use preheat. Just got a new battery on. I will try to pump it 8-10 times next time and see if it helps. Best regards

[omega708]

Europe, Denmark - currently the temperatures is -5 to +5 celcius. I normally prime it 4 times during the winter, 2 during the summer. I do not use preheat. Just got a new battery on. I will try to pump it 8-10 times next time and see if it helps. Best regards

I typically only need 2-3 pumps when the temps are at or above 15 C.  Anything colder than that and I have to increase the number of pumps.  Temps of -2 to -5 C requires 10-12 pumps in my plane.

[Awful_Charlie]

If it is starting but then dying, the battery is ok, and as others have indicated, it sounds like fuel.  If you don't prime an injected engine enough, it fires, runs up, and then dies, sounds very similar