Background... OS-160FX, Slimline Pitts Muffler w/straight pipes (no rolled ends). Very wide adjustment range. Constant dead sticks, poor run around mid range, got hot died.
I read all the posts, and installed large fuel lines, Perry Pump VP-30. Ran great on Ground. Flies good once in a while, but still dead stick about every other flight. Usually quite
hot.

Pulled tank, replaced lines, checked for leaks/pin holes found none. This time I ran it with cowl off as we were starting to think I just needed more airflow. Noticed that as I
stat leaning the high end, and get probably 800 RPMs from peak, there was a LOT of air in the carb line, so if allowed to continued would lean, get hot, and die. I let it cool, and ran it again.
there is no noticeable air into the pump, but air all the way from the pump to the carb. I replaced the large lines from the filter (before pump) all the way to the carb, with medium line, and zip tied all
connections. Ran it tonight, and it seems better, but at full throttle, after a few seconds at about 500 RPMS before peak, it will still pump a lot of air into the line at the pump.
The only thing I can think is: either the needle valve is leaking, but then I should not have air between it and the pump. Soooo Must be the pump. It is new, and I have only adjusted it about 1-2 turns in or out, not even close to
the limit either at end.

Any thoughts would be very helpful.

Les

I spoke to Gary at Perry yesterday and he said to me that if there is no air going in but visibly air going out then it is the pump. That said i have been tryimng to get mine running and am also experiencing a significant drop in RPM but i can't see it being due to air in the line.

Flathead:

Listen to Gary. If air is entering at the pump you have a leak in the diaphragm. Send it back for exchange.

Bill.

Sorry Bill you'Ve confused me a bit there.
If thers no air going in then it is the pump. Mine has from what i can see no air going in or out so that would suggest that it is the settings.
I think you may have picked up on something i wrote on another thread about fitting a return line which unfortunately doesn't semm to have worked. In facy the problem of tilting vertical and the engine dying has come back. Any clue?
Thanks

Spinner:

You're right, It was Iffy Les, first post in this thread, that had the air getting in at the pump. A pin hole in the diaphragm will allow some of the crankcase pressure gases to get on the fuel side, giving the air in the delivered fuel. He is the one who needs to return the pump.

I really don't know any more to say on yours, it just sounds like you're not getting sufficient fuel delivery, but I've never had that problem on an engine up to 1.50cid.

Maybe you should return yours and ask that it be tested for volume of delivery.

Bill.

I think both of you were responding to my problem. I have NO air in, but lots out at high rpms.
I will see if they will exchange it Monday... Thanks to both of you for responding..

Les

I called Gary at Perry, He was very nice, and after a couple questions, said "no problem, I'll send you a new one"..He said it sounded like a leak. Got the new one today, hope to get it running this weekend, and will
post the results.. Great customer service!

Les