[Marcus Sowl]

Marcus Sowl on April 3, 2015 at 9:49 am #17677

I ran the idle mixture test as suggested by Steve Ells. At idle, and leaning, the RPM increased by over 200RPM! Geez, maybe this has been the trouble all along. I’ll get with the A&P and let him know. Thank you.

[Anonymous]

Anonymous on April 3, 2015 at 9:39 am #17676

Good luck on solving the problem by next winter. In the meantime, enjoy the warmer months. Thanks again for sharing your information.

Scott Sherer
N344TB

[Marcus Sowl]

Marcus Sowl on March 31, 2015 at 8:18 am #17669

Thanks for the help in this matter. We actually haven’t come to a resolution. We’ve never found water or debris in the fuel system. We’ve replaced the engine driven pump and the fuel servo with no change.
I think there is a probability that we do have a mixture setting issue as was suggested. Perhaps we’ve been running too rich in the winter. Very difficult to tell. With the warmer weather we have had no problems.
We’re considering installing a winter kit of some kind for next winter.
Very frustrating and obviously concerning.
Thanks again for the help. I’ll post any new information.

[Anonymous]

Anonymous on March 30, 2015 at 5:50 pm #17662

Hi Marcus,

We haven’t heard anything from you in a while regarding your rough engine problem. Have you pursued the problem further since Steve Ells last sent you a message? Let us know, we’re all curious about the outcome and we’d love to hear that you’ve solved it!

Best,
Scott Sherer
N344TB

[STEVE]

STEVE on March 10, 2015 at 7:59 am #17652

Hi again.
After re-visiting your write up it appears that in addition to the water from condensation, you have an idle mixture problem.
It’s important to re-set the idle mixture and idle speed with seasonal changes. If that wasn’t done it may explain the spark plug fouling and hard starting problems. The simple test to determine if the idle mixture is set correctly is to slowly pull the mixture control knob aft at idle rpm. Some maintenance texts suggest doing this test at 600 rpm; some at 1000 rpm. A properly set idle mixture will cause a slight (25-50) rpm rise prior to engine cut off.
If you have an analog tachometer it may not show this slight change but you’ll be able to hear the rise if it’s there.
It the rpm increase is greater than 50 rpm the mixture is set too rich; if there’s no rise, the mixture is too lean.

[STEVE]

STEVE on March 6, 2015 at 9:50 am #17651

It sounds like you’re getting little bits of water in the fuel. Not enough to cause a real emergency or loss of power but enough to cause a tighter grip on the yoke. The most common causes are a leaky fuel cap or condensation.
Try the following; shake the wings up and down as best you can by putting your one hand on top of the wing and one hand on the bottom of the wing at the wing spar and do your best to move the wing up and down. The idea is to dislodge any water globules and get them flowing to the fuel sump drain. Then drain a lot of fuel out of the right tank. Might as well do the left tank too since you’ll be warmed up.
The next thing to do is add isopropyl alcohol to the fuel tank. The alcohol absorbs water and prevents water in the fuel from freezing. Don’t use rubbing alcohol even though it does contain isopropyl alcohol; it’s diluted.
For 30 gallons of fuel add 5 cups of alcohol. If you’re having a hard time rounding up isopropyl alcohol, you can order PRIST HI-FLASH LO-FLO from Aircraft Spruce and Specialty: https://www.aircraftspruce.com/catalog/eppages/FBprist2.php.
Try that, let me know how it works.
Steve

[Anonymous]

Anonymous on March 2, 2015 at 6:50 pm #17650

Thanks, I’m doing a bit of research.

Scott Sherer
N344TB

[Marcus Sowl]

Marcus Sowl on March 2, 2015 at 7:44 am #17649

After flying the Arrow on four separate occasions, about one hour each flight, I found that engine faltering only on the Right fuel tank was only coincidental. It also faltered on the Left tank. Additionally, the engine faltered on taxi as well. Very annoying.
Outside temperature well below -18 C in all cases.

[Anonymous]

Anonymous on March 1, 2015 at 8:27 am #17643

Hi Marcus,
I’m going to take a screen print of this thread to my mechanic tomorrow and ask for his opinion.

Scott Sherer
N344TB

[Marcus Sowl]

Marcus Sowl on March 1, 2015 at 6:20 am #17642

Additional information on this topic:
1) This phenomenon only occurs in cold weather
2) Primarily occurs in a nose up pitch attitude
3) Did not occur before we had a heated hangar
4) There is a delay of at least 30-60 minutes after leaving hangar before it happens. Evidently dependent on outside temperature
5) When it occurred for the first time last winter it took about 45 mn and was departing DLH, nose up.
6) Perhaps water is condensing because of temperature change from hangar to outside cold, somewhere in the fuel system, probably on the right side, and then freezing creating ice crystals causing a partial restriction of fuel flow
7) I’m wondering why it occurs in a nose up pitch. Is a vent getting blocked?
8) Electric fuel pump has no effect.
We have replaced the fuel pump and had the fuel servo rebuilt; although these parts were in need of repair, they evidently did not contribute to the problem.
I will fly today and will do a significant drain on the right side fuel tank, fly for an hour or so and see what happens. If the problem occurs, I will rtb and add isopropyl alcohol to the tank and fly again to test.

I’m looking forward to suggestions for this extensive, helpful knowledge base. Thank you!