All,

I have been catching fits with a recent installation of any engine I try on my 40 size ME 109. After a recent nose over and subsequent engine mount replacement, I have been unable to get any engine that I try to maintain high end operation.

After several hours discussing this problem with many of the club members in my home club and also with folks at local hobby shops, I have been given the following items of potential concern:

Vibrations creating bubbles in the fuel system and engine essentially not getting fuel from tank.

Replace foam, tank fittings and all fuel hose.

Vibrations coming from some other location within the aircraft might consider epoxy and support ribs in strategic locations.

Check tank height relative to spray bar for inverse mount engine installation.

If there are any other persons who have had this experience (where no matter how much I open the needle valve on the high end engine will die due to loss of fuel flow to carb)

Please Help.

This happens with more than one engine?

If it were just the one engine you crashed, here are some things to check:

1. Crud in the needle valve. Remove the needle valve and pump some fuel in through the carburetor inlet nipple.
2. Low speed mixture set too lean. Put a length of clean fuel tubing on the carburetor inlet. Set the carb at idle. Blow in through the tubing, and turn the low speed mixture adjustment counter clockwise until you can hear air hissing from the carburetor.

If you have more than one engine with this problem, it's highly unlikely that both engines are affected by the above. The problem must then lie with the fuel system.

Make sure EVERYTHING is replaced with new, known-good parts. Pressurize the fuel tank with a basketball pump, clamp off the lines, and submerge the whole thing in a bucket of water. If you see bubbles, you have an air leak. Fix it.

Make sure the tank is LOOSELY packed in foam. If the foam is packed tight, it's no better than gluing the tank directly to the structure of the airplane.

Balance your propeller. Using the same propeller on all the engines? If it's badly out of balance, it will shake the fuel tank no matter how well you pad it.

had that problem with a new k and b 40, with a slimline muffler. Turned out the muffler had too little volume, and was actuly creating suction, instead of pressure. Capped off one of the exhaust tubes, installed the pressure tap in the blocked tube, problem solved. I could take the needl all the way out, and it ran lean before that!
good luck!
d

Have you checked that your clunk line inside the tank is not flipped forward, pinching off the fuel?

I had this problem with a Webra 120. I checked all the usual suspects to no avail. We spent hours checking fuel line, o-rings, tank, blah, blah, blah. Guess what, it was number 2. Low speed mixture set too lean. It was so lean that the spray bar was still mostly blocked by the low speed needle at w.o.t. One of the teenage kids at my field suggested checking it. The old timers learned a thing that day.