Hi Shane;
Great news. Thanks for helping other Piper Flyer forum readers follow along on your quest and for sharing the solution.
Happy Flying
Steve
Archer II hesitation at 1500 RPM
-
ParticipantParticipant
We solved the Archer II hesitation!!!
I hate seeing a problem posted and never find what the resolution is. Here is what we found on our issue:
As stated below, I had a hesitation at 1300 RPM (not 1500 like I originally thought). This hesitation happened when normally applying power – not abruptly. This was with the carb that was on our plane when we bought it last year. When we completed our first annual, My IA recommended we install an overhauled carb and it would take care of the issue. We did and it didn’t.
We (my IA and myself) tested and retested the newly overhauled carb. We found that if we leaned the mixture out (way out) it would not hesitate. We also noticed that in that 1300 RPM range, our cylinder and EGT temps were dropping. Below or above 1300 RPM the temps would climb. This told us certainly the carb was running rich. We checked for intake leaks. We removed the primer system from the loop to make sure it wasn’t dumping fuel into the cylinders. We removed the air box and all still gave the same results.
We called Marvel Schebler carbs and spoke with Jess (I believe). He pulled the overhaul info and said it was all within Lycoming spec. He suggested we lean out the carb where it doesn’t hesitate, turn off the fuel until the engine quits, then use feeler gauges and measure where the mixture linkage was positioned and send the carb back. Once he received the carb, he ran it through tests and said it was still within Lycoming specs. He also said he had not heard of any “issues” like we experienced. I found numerous complaints on the web with Piper Cherokees with 180HP engines. Most pilots said they just lived with the hesitation and sputtering. Me… It made my stomach knot up if I was on final and needed to add just a bit of power and my engine hesitated.
Marvel Schebler (Jess) adjusted the jet that was affecting the carb in that 1300 RPM range. He said it was still in spec but was now on the lean end.
We received the carb back, reinstalled and it runs flawlessly!
Thank you Steve Ells for your help and input. I will definitely pass on this info when I read about it in forums. Marvel Schebler carbs were great and painless to deal with.Thanks
ShaneParticipantHi Shane;
The fact that you can lean the mixture and you get no hesitation tells me that it’s still a mixture (carbuetor) problem. And as I said before it sounds like it’s in the transition range between idle and normal metering.I believe the best carburetor people are the folks that hold the type certificate. They are Marvel Schebler carbs at http://www.msacarbs.com in Gibsonville, N. C. I recommend that you call them at 855 672-2272 and tell them your problem. They will suggest that you send them the carb so they can test the mixture and flow ranges on their flow bench. That’s the only way you’re going to be able to determine is it’s the carb.
Please let me know how this turns out.
Best,
SteveParticipantWe just installed an overhauled Marvel-Schebler carb in June during annual. The previous carb was hesitating as well. It was recommended that we install a rebuilt or rebuild ours. We elected to purchase an overhauled carb from A.E.R.O.
As previously mentioned – this hesitation seems to be common on Piper Cherokees with 180 HP Lycoming engines. I have found very little info on what a cure is.ParticipantWhen was the last time the carburetor was overhauled? I am wondering if the float is in properly adjusted or the floats partially deteriorated. They have had a lot of issues with the floats over the years.
ParticipantSteve Ells,
Thank you for the suggestions. Myself and my IA have been trying to solve this hesitation with no luck. We have tried to adjust the mixture and no matter where the setting is , we still have hesitation.
We did a leak test on the induction system yesterday and found no leaks. We checked everything and everywhere we could possibly check.
Tempest suggested we may have a leaking fuel primer, so we blocked off the system and still see the same results. (we checked the fuel primer system for leaks as well).
Let me clarify a few things from my first post now that I have tested and tested: The hesitation happens right at 1300 RPM consistently. It happens when advancing the throttle slowly. I tried fast and slow and it makes no difference. During ground testing, If I lean the mixture (right before cutoff) I can advance the throttle and we have no hesitation, so this tells us we are too rich. However the carburetor is adjusted correctly (around 2 turns out on the mixture needle) we get a 50 RPM rise right before cut off. The plane fly’s fine. I have been told it is just a nuisance. Regardless I would love to find the culprit of this hesitation.
Thanks
ShaneParticipantHi,
It sounds like you have a problem in the transition range of the carburetor when fuel flow goes from the idle circuit to the main jet circuit.
I have two suggestions.
1) Make sure the idle mixture is correct. Here’s how. Screw the mixture needle in slowly until it seats. (gently!) Then back it out 2 turns. That should get you in the ballpark. The mixture is correct if you get about a 25 to 50 rpm rise when you pull the mixture to shut the engine down after a flight. More rise?? It’s too rich. Drops off immediately with no rise?? Too lean.
2) leak check your induction system. You can do this by applying 10 psi of air pressure to the system with a cylinder compression tester. Move the prop until the exhaust valve is closed and intake valve is opened. Plug the air inlet then spray soapy water on the inlet tubes, the gasket between the carburetor and the intake flange, and where the intake tubes meet the cylinders.
There might also be an air leak in the manifold pressure fitting or hose.
Please let us know what you find.
Thanks
SteveParticipantI have seen this topic all over the internet but have found little info on actual cures. We have a 1977 PA 28-181 with O-360. When we purchased the plane the broker commented to “SLOWLY” apply power. After much flying I notice on ground run up, take off or final if I transition from low power (800-1000 RPM) to full power quickly, we get a hesitation at or around 1500 RPM. Our annual last month included an overhauled Marvel-Schebler carb and a pretty extensive annual. Now that I have flown the plane 2 or 3 times and played with power settings, I notice the hesitation is still apparent. Our A&P/IA said we replaced everything that could be the culprit.
Any suggestions that have worked or solved the problem?
I read that this is so common with Cherokees with 180HP that it is standard and accepted.
Viewing 8 posts - 1 through 8 (of 8 total)
- You must be logged in to reply to this topic.
