As I understand it, the injectors are staged. The
secondaries only cut in at a certain rpm. So, if you're rpm is below the
staging point, and you kill the primaries you have no fuel and engine will
quit. Above the staging point the secondaries would be supplying fuel. Just a
theory, but it makes sense to me...
I was thinking that Tracy took this into account,
but after reading the instructions again, it does look like he just depends on
the cold start function to add fuel. I guess you won’t be using any
power setting below the secondary staging point during normal flight, except
for maybe a steep descent.
Of course I have to wonder, why not just
run them all, all the time? Mazda probably made them staged for
emissions, or drivability, but there are FD guys running four 1600 injectors, who
seem to idle just fine with two 1600 injectors. Surely I can idle with
four 550’s. I think the staging point is adjustable, but I’ll
have to look at the manual again tomorrow. I might just be tempted to try
running all four full time.
Rusty