I recently had N84MR in for it’s first real inspection (a mini-100-hr).
Everything checked out really well… until, after it was all buttoned up, I got a call from the Authorized Service Center asking “Do you have any special tricks to starting your engine?”
So I told them… Yes… I’ve found that if I get it good and warm (Reiff preheat), prime for a really long time (40 seconds), and “punch” the primer button repeatedly and frequently during cranking, it starts with no problem, although it takes awhile, and I can’t open the throttle beyond a crack for about two minutes without it coughing and often dying.
This got a response of “It shouldn’t be that way”. I hadn’t questioned the behavior because of all the previous discussion here about how hard it can be to start the engine; I was simply happy to have found a technique that works reliably.
The A&P told me that clearly there was not enough fuel getting to the injector manifold; and that maybe I need a new fuel pump. He would discuss it with Cirrus.
What he learned is that the fuel pump has an adjustable voltage limiting device on it, which may have been set too low (it was). He later explained to me that there is a poppet valve in the injector manifold, and the fuel pump was not generating sufficient pressure to lift it. If the poppet valve doesn’t open, it matters not how long you prime - no fuel will get into the manifold. The reason it worked for me is that with each “punch” of the primer switch, a little bit of fuel made it into the manifold as the pump first started, before the limiting circuit kicked in. With enough of those little squirts, the engine would start (but not run very happily at first).
The (happy) end of the story is that now my SR20 has gone from being among the most difficult of engines to start, to being about the easiest of all in my experience. This problem and fix may have been unique to me, but I suspect not. In any event, it’s well worth looking into.