Mercury 200 OptiMax Jet Drive Service Manual page 215

Direct Fuel Injection
A tracker diaphragm is used to maintain a constant pressure difference between the fuel pressure and air pressure inside the fuel
rails at all times. The tracker diaphragm minimizes the pressure changes caused by the air compressor pulses and fuel injectors
at lower engine RPM. The tracker diaphragm is located between the fuel and air chambers on the fuel rail. The tracker diaphragm
will expand into the lower pressure chamber side of the fuel rail when a pressure spike occurs.
NOTE: To prevent excessive wear in the seat, the tracker is calibrated to allow the diaphragm to be slightly away from the seat
during normal operation.
i
h
i
h
Page 3B-52
a
b
c
d
e
f
g
36088
a
b
c
e
f
g
36091
Engine off (no pressure)
a - Top cover
b - Spring retainer (not shown)
c - Spring
d - O‑ring
e - Diaphragm seat
f - Air rail
g - Air passage
h - Fuel inlet passage
i - Diaphragm assembly
Engine at operating pressures
a - Top cover
b - Spring retainer (not shown)
c - Spring
d - O‑ring
e - Diaphragm seat
d
f - Air rail
g - Air passage
h - Fuel inlet passage
i - Diaphragm assembly
90-8M0050731 MAY 2011