Engine keeps quiting

[Arnieb]

My Sonex has a Jabiru 3300A with a Aerocarb I bought the airplane already built it had 1 hour flight time on it. Since then I put 6.1 hours in the air but keep having engine problems. It hasn't quit in the air thank God but has as soon as I got it on the ground. I was told at the EAA that it was most likely vapor lock,so I wrapped the fuel lines and the exhaust. The next flight I was getting high CHT and was told that the cowling openings weren't large enough so I corrected that problem. Then took it up in the air again and could tell the engine wasn't running right so got it on the ground and put it in the hanger. Talking to people they said are you sure that you weren't just imagining it because of the past history and I thought well maybe that was the case. I decided to try it again and the engine quit 3 times just taxiing out to the end of the runway, so I am fed up and decided that I am going to sell the plane for what I owe on it. Anyone out there want to take on the project and buy a Sonex for $21000 let me know.

[vigilant104]

Arnieb,
- Did the builder of the plane have any useful information?
- As your plane has an Aerocarb (as mine does), have done research on "the burps?" If your engine is experiencing these problems primarily when it is hot under the cowl (e.g. when you are running on the ground without much airflow), you may have "the burps." They are caused when fuel vaporizes and forms bubbles in the fuel line. When these bubbles reach the Aerocrb,, the result in a short period when no fuel is dripping through the tapered pin. The same bubbles might form in a plane with a regular float bowl crb, but they would be unnoticed in that case due to the relatively large volume of fuel in those carbs. Normally, the burps result in short periods of stumbling, but the engine does keep running.
The problem can be addressed in several ways. Insulating the fuel lines helps a lot. Also, many people eliminate the gascolator, which gives the fuel less time to get hot under the cowl. Some people have fitted a small return/vent line to allow the bubbles to escape before entering the Aerocarb. Running 100LL rather than gasoline helps, and any ethanol in any fuel will add to the problem.
I'd suggest you do some searches here and read up on the issue, it used to be a common one before it was identified and addressed. At the very worst, you could look for another carb, but many folks have successfully gotten their Aerocarb to work reliably. It's no reason to throw in the towel, there are lots of folks here to help.

[kmacht]

High chts and the engine cutting out sounds like it may be too lean. Have you tried tuning the carb per the aerocarb manual? Taken a look at the finger screen in the tank to make sure it isn't plugged up? Do you have a gascolator installed?

Keith

[fastj22]

Sounds like a lean situation. Do you know what your EGTs are? Try setting your needle ¼ turn rich (out). You may need to lean with your mixture control after startup.
I have mine set pretty rich and have to pull the mixture about half way after startup. Then adjust as needed. I rarely go full mixture unless traveling down to sea level. If the ¼ turn helps, but still too lean, go another ¼ turn. In flight I try to lean to around 1350 EGT in cruise. 1200 or so in climb.