G'day
My 120ax os is playing up.
Here are the symptoms:
When running at Idle it is running fast I think it maybe a touch lean
Mid range it is richening up[&:]
High speed it is acting as though it is running lean again, but it is 300 rpm off peak
The pery pump is way off the pressure the srew is almost about to come out.
I can't understand that if the pressure is off on the pump and both the high and low end is runing a little lean why is the mid range richening up. Can some one help me tune my engine please?

what type fuel and could be perforated diaphram in pump try hooking direct to carb and bypassing pump see if different otherwise screw is backed out too far on pump

also check and make sure you are not drawing air from tank and you are not sufering fuel foam problems

also carterrc you can go to rcwarbirds.com click on engine forums man knows his stuff he has helped greatly in the past

Get about 3 feet of fuel tubing and add a tee in the fuel line. Put the three feet of tubing to the tee, keep the other end open. Raise the fuel tube above the engine, tape it to a stick or anything to keep it elevated. Start the engine. If the pump regulator is operating correctly and it is adjusted to the low setting the level should be less than 10 inches. High pressure may be near the top of the line. If it is too high and you cannot adjust lower then consider sending back to Conley, though I don't know if they will replace it.

Other than that you may be using too hot or cold of a glow plug. Not sure because I'm not sure how the pump is set up. You may actually be three hundred RPM lean of peak, the pump regulator sometimes does not alway self adjust right away (especially if gummed up with castor) and it may be leaning out as you are adjusting the needle. You can check if the pressure is going up and then down by observing the level in the elevated fuel tubing. Richen the needle up and wait a minute or so to be sure this is not happening.


be aware that I have not done this myself, but have read about this somewhere and am theorizing to some extent.

I thought on the Perry that CLOCKWISE - INCREASED pressure? Sounds like you may have the pump super lean........

Hi!
Why do you mess with a pump when it isn't necessary to use one...?
Regards!
Jan K
Sweden

He said he reduced pressure because of a rich midrange.

G'day
Sport Pilot I am definately rich 300 rpm rich off peak on the top as when I lean out the high speed less smoke comes out and the pitch of the engine ound changes. I will try what you suggested though.

G'day
is it possible for the perry pump to be set too lean on the pressure if so what characteristics am I looking for to find this out?

I have perry pumps working on webra 1.20 ok.
What I have learned is that at least on webra engines idle screw also affects mid range and transient from midrange to full throtle, you may try close idle screw a little biut and you might notice difference.
What I suffered for quite a while was the same thing, idle Ok, full thgrotle Ok, but when taxing to runway the engine goit flooded and turned off, I then closed idle a little bit and no problem.
The other thing I learned about perry pumps is that the screw doesn't make bid differences, you can turn it a full turn and no difference.
Hope it helps
regards
Omar

If it won't adjust the pressure, then something is wrong with the pump, send it back if still under warrenty. If not then perhaps you could add a return line form the pump outlet to just before the carb and back to the tank. That way the pump supplies fuel at a minimum pressure.