Bruce, re fuel pressure issues with the CAMIT engine.
There is quite a bit of discussion on the Yahoo Jabiru and Camit Aircraft engines group.
I would contact CAMIT in the first instance based on Ian's findings into similar problems.
Here is Ian Bent's response, there are about 50 messages in the thread (not sure if you have to join group to view )
https://groups.yahoo.com/neo/groups/JabCamit/conversations/messages/454
"The fuel pump issue is developing into a root-cause issue which needs to be fully understood.
We could easily just fit a stronger spring which “may” work most of the time.
The starting point has been that the CAE spring outputs 2-2.5 PSI during dyno testing where the pump is raising fuel from a small tank positioned below the pump (on the floor, outside the test-cell to prevent siphoning –fires)
The fuel supply line is as long and small as in any recreational aircraft. Why is a stronger spring required?
We’re finding significant problems with aircraft installations. Free flows (no electric pump) as low as 12LPH (3.1GPH) have been found in an installation where the engine needed at least 40 LPH at full throttle. The difference between the two means that there will be a reduced pressure at the pump inlet which will reduce the efficiency of the mechanical pump. Apart from the potential for partial leaning at high power settings, this will also affect the fuel vaporisation characteristics of the fuel (more so with unleaded).
Using an emergency pump to conduct a fuel flow test may not be an appropriate procedure as the emergency pump is not used at all times by all pilots. It should be considered as part of a separate, redundant system.
The mechanical pump is usually less efficient due to positioning (drawing instead of pushing fuel) so the test should make sure the mechanical pump is able to supply enough fuel “plus a margin” to allow for system degradation between annuals.
There are a lot more factors to be considered here such as, added fuel system components(fuel flow sensors), non-serviceable tank finger filters, aged fuel, tank linings, alcohol, etc. so the problem is how best to adequately test the fuel system in a simple manner. We will be able to supply stronger springs in app 1 week which seems to solve the apparent problem in some installations, but I don’t see this as a first option. The plan at the moment is to make sure that fuel systems are able to be appropriately tested before making changes which don’t necessarily address the root cause issue.
Ian
CAMit "