Interesting ''First Flight',

[DanBaier]

I've had a bad carb (new) before - it does happen.

As previous have said, double check the fuel pump & carb to be sure correct for the engine.

Also keep in mind that the MS carbs have a distinct idle circuit - adjusting the mixture with the engine running at low speed (should probably be north of 1500) is not likely to be productive.

I might have missed which prop you have, but if FP and it turns normal static RPM on the ground, then I'd also check to be sure that when the aircraft pitches up (as in climb), that you don't encounter a situation where air is drawn into the fuel line through the gascolator drain (or other leaking fitting - a situation that, while not common, can happen in a Piper Cherokee and produces a result much like described by the OP).

Dan

[RV-4]

Good Morning Gents

I send the link to this page to my friend and he is monitoring it for suggestions and ideas.

He might post whenever he has a minute.He is at the hangar right now working on possible solution.

I'll try to get the engine Type ( I know it is an 0-320 but don't have the dash # ) and the carburetor and fuel pump models so we can troubleshoot the possibilities of a wrong type being installed.

I will keep you posted.

Thanks

Bruno

[RV-4]

Update

My friend kept on troubleshooting the possibles causes as to what may have cause this behavior and he's starting to corner the culprits..

High Fuel Press: Faulty reading due to a programming error which has been rectified ..

As to the engine coughing on take -off, this behavior as he stated , started at about 90-100 MPH and the possibility right now is that there may have been air entering the fuel system thru the gascolator as suggested by someone here VAF (Thank you very much BTW ) and a local mechanic at his airport.

At the request on the MD-RA ( Cdn local inspector, just like a DAR in the US )he had to install an evacuation tube at the gascolator and this tube was bend forward slightly and may have allowed air to enter the system while under pressure.

This tube has been removed for now.

He will also install a new Carburator on Monday and see if he can lean the mixture with the new one.He says that he is confident it will work.

He told me that he will pipe in later on to share his findings and results with all of us here on VAF.

Once again thank you all for your feedback's and advises, they were very appreciated.

Bruno
rv4@videotron.ca

[videobobk]

Don't EVER let anyone tell you a mechanical pump can't fail to high pressure! Our 9A had an O-320 with 885 hours that had been stored for less than a year. It gave a high fuel pressure indication. We did all the right things--checked the gauge, tried with and without the electric boost pump, and had the carb float checked and then rebuilt (it was overflowing.) Five (count 'em) A&Ps told me a pump couldn't fail to the high side, but a new pump cured everything. No, I don't know exactly how high the pressure was, because we would have had to plug the pump outlet as the carb float valve was sort of a "pop-off" valve at that point. I suspect it was 12-20 psi. We knew it was the mechanical pump when we bypassed it with a solid line, and the engine ran great on the electric pump. Theory is that gunk had gotten onto one side of the diaphram when the engine was stored nose-up with old oil. Seven years later, the engine still preforms great, compressions never below 76/80, and never a fuel related problem.

Bob

[Mousse]

Hi everyone,
I am the one who experienced this less than perfect first flight. First I would like to thank Bruno and all who contributed their help in finding solutions to my problems.
I believe the high fuel pressure is taken care of and I will be contacting Dynon to ascertain the proper sensor setting to be used. At least now, the reading is zero with the engine off. There are seven possible settings on the EMS-D10, I have eliminated the first four and 3 are showing 0 psi now, so will find out which one to use talking to Dynon.
As Bruno has mentioned in a previous post, I strongly believe that the culprit for the rough engine was due to air entering the fuel system through a misaligned gazcolator drain tube. This has been corrected as well.
I will install a different carb to-morrow and hopefully the inability to lean will be taken care of. As it stands now, impossible to adjust the idle mixture (no visible increase in rpm when pulling mixture at idle-cut off.) and when leaning at WOT, the engine would just quit without any sign of leaning.
Thanks again and stay tuned.
Michel

[dynonsupport]

Michel,
A correctly tuned fuel system will show almost no increase in RPM at sea level. The increase is because you lean through peak power, but the carb should already be at peak power at idle on the ground at sea level. It may also be already lean if it isn't adjusted right so all you will see is a decrease. So that may be a red herring.

Do you have fuel flow with your D10?

[Mousse]

Thanks Dynon for your comments. No, I do not have fuel flow at this time.
Michel

[BobTurner]

Originally Posted by dynonsupport

Michel,
A correctly tuned fuel system will show almost no increase in RPM at sea level. The increase is because you lean through peak power, but the carb should already be at peak power at idle on the ground at sea level. It may also be already lean if it isn't adjusted right so all you will see is a decrease. So that may be a red herring.

Do you have fuel flow with your D10?

I believe most engines are set up to be rich of best power at full rich, for detonation margins. Back in my O-470 days the manual was very clear; going to idle cut off should produce a momentary rpm rise.

[flyenforfun]

We have a Dynon skyview and ours read 35 PSI when we first ran it and it turned out to be the wrong settings in the skyview set up menu. I don't think the rough running and the 35 PSI are related.

[dynonsupport]

Bob,
Totally depends on how your fuel system works. I agree that when producing flight power, they are rich. However, many have a totally independent idle adjustment.

Also, since this is not yet a tuned system, it could be mis-adjusted. I was only pointing out that the lack of the RPM increasing when it was leaned was not an indication that it wasn't leaning at all. Just that you could be starting at peak or lean, and thus an increase is not expected.

You should be able to watch EGT's as well and get a sense if you are leaning successfully or not. You can generally do a peak check pretty effectively at about 2,000 RPM, just above normal MAG check power levels.

--Ian Jordan
Dynon Avionics