Exhaust fumes in cockpit when doing slow flights/stalls and fuel too rich

[vickytori]

We began flying May 3, 2013!!! Going through the maneuvers, during slow flight, etc. exhaust fumes are smelled in the cockpit. Anyone else have this happen? Also, our airport is at 5,100'. We are experiencing per our EFIS, 6 gallons per hour.going to do a few more tests. Any ideas?


Began construction May 5, 2012, first flight May 3, 2013.

 

[Mich48041]

Check the tension of the muffler springs. Read this thread:
http://www.vansairforce.com/community/showthread.php?t=97629
When it is dark, hold a bright light on one side of the firewall and look for light shining through on the other side. Seal any holes.
Do not believe the EFIS fuel flow until it has been calibrated and verified.
Joe Gores

 

[Lemmingman]

Wow! 1-year from the beginning to the first flight. Way to go.

 

[BigJohn]

......Also, our airport is at 5,100'. We are experiencing per our EFIS, 6 gallons per hour.going to do a few more tests. ....

Several of us experienced a phenomenon where the indicated fuel flow jumps quite high when above about 6000MSL or so. Seems to be related to the extra pressure from the electric boost pump. Onset can be quite startling due to high flow alarms and such. Some folks installed a switch so the pump can be turned off at high altitude. Just a FYI. John

 

[ArlingtonRV]

Similar Experience

During flight testing I had a very sensitive CO detector in the airplane. I found that it would go off when at a high power setting, nose high attitude and low airspeed. I did a very good job of sealing the firewall and found no significant source of air leaks there.

Note the position of the exhaust tube through the bottom cowl relative to the leading edge of the wing. What I believe I was experiencing was that in that condition the airflow around the front of the fuselage changed a little and the exhaust stream was entering the slipstream around the fuselage and entering through the gap between the canopy and the fuselage. I did put some weatherstripping around the base of the canopy and it got a little better, but I was never able to completely alleviate this situation.

The CO detector that I used started to indicate at 8 PPM and I usually saw 12 PPM in climb. It never went above 20 PPM. In cruise it would drop off to 0. I just kept these umbers in the back of my mind and tried to minimize high power low airspeed operations.

I also noticed that the detector would go off intermittently in cruise above about 8000'. I just attributed that to the detector not being specifically designed for aviation and was probably fooled by the thinner air.

 

[RFSchaller]

I've experienced both issues. The exhaust smell seems to come in through my right vent. I had a hi-fuel flow alarm (red cube sensor and D-180) right at lift off after about 30 hours. I checked the fuel system from tank to carb and found no leaks, so I moved the alarm set point and had no more alarms. I have noticed that gradually my fuel flow indication increased after calibration. Actual fuel consumption never changed.