Changing the diaphragm in the aneroid should have no effect on a fuel leak from the breather, unless it wasn’t really fuel leaking but was oil
-The chamber above the diaphragm should be completely free of liquid with the possible exception of a little oil
which might be leaking past the turbo seals
. Changes in turbo boost pressure are felt in that chamber which move the diaphragm up and down.
-The chamber below the diaphragm is also normally free of liquid, and the volume of that chamber expands and contracts in response to the movement of the diaphragm. The air normally in that chamber moves in and out breather #45 in response to the volume changes. If the diaphragm had a split in it you might see some oil leak
out the breather.....assuming there was some oil above the diaphragm.
-The area of the pump
below the top cover is full of fuel and is normally isolated from the upper chambers by an O ring.
In your parts breakdown, parts # 4,5,6,7,8,23,&25 consist of the linkage that are moved by the diaphragm in response to boost increase and decrease. Their locations on the drawing are distorted...they really reside in the left side of the top cover, and #23 &25 are below the cover residing in the fuel. Pin#8 resides in a drilling that passes from the fuel chamber into the area below the diaphragm, and it is sealed by O ring #6. If this O ring develops wear, it will allow fuel to move from the lower section of the pump
into the chamber beneath the diaphragm, and thus out the breather.
Besides having an external lift
pump in the fuel system, there is also an internal gear
pump within the injection pump which changes the internal pump fuel pressure. As the RPM
goes up the pressure increases and this operates the injection timing piston and also ensures good injection chamber filling. It’s this internal pressure change that is probably causing the lack of leak at low rpm
but leak at higher rpm.
It’s possible that a blockage in the fuel return line, as mentioned by skipperpete, could be causing some leakage as a result of pressure buildup in the injection pump, and that’s easy to check. My experience with blocked fuel return lines is frequently associated with excessive fuel injection and smokey exhaust
. You might also check the return fuel banjo bolt on the injection pump. It normally has a restricting orifice in the bolt, and if this were blocked it might also cause a pressure buildup and subsequent leak.
Hope this helps...