Mercury 200 OptiMax Jet Drive Service Manual page 191

Direct Fuel Injection
Component or Problem
Fuel pressure and air pressure are
both low
Fuel pressure and air pressure are
both low
Fuel pressure and air pressure are
both low
Fuel pressure is low or fuel
pressure drops while running
Air pressure remains normal
Page 3B-28
Possible Causes
Air compressor
Air compressor inlet
Starboard rail air inlet
hose
Starboard to port rail air
transfer hose
Tracker valve
Direct injector
Air regulator
(This should be the last
component to check/
remove)
Air rail test (Schrader)
valve
Tracker valve
Fuel hoses
Fuel regulator
Corrective Action
Provide 80 psi of shop air to the air rail test (Schrader) valve.
Inspect the air compressor for leaks. Leaking air through the
compressor indicated bad reeds.
Inspect for broken reeds.
Remove the air compressor cylinder head and inspect the
cylinder wall and piston for scuffing.
Replace components as necessary.
Inspect the compressor air inlet for blockage, kinks, or tears.
Clean, correct, or replace components as necessary.
Inspect the air inlet hose to the starboard rail for blockage,
kinks, or tears.
Clean, correct, or replace components as necessary.
Inspect the air transfer hose from the starboard to port rails for
blockage, kinks, or tears.
Clean, correct, or replace components as necessary.
Remove/inspect the tracker valve diaphragm for cuts, tears, or
abrasions.
Inspect the diaphragm seat and rail for damage. Replace
components as necessary.
Injector may be damaged or stuck open. Perform a resistance
check or leak test to determine cause.
Check O‑ring for nicks or cuts.
Provide 80 psi of shop air to the air rail test (Schrader) valve.
Visually inspect the air regulator cover. If air is escaping through
the small hole, the regulator is faulty. Replace the port fuel rail.
If necessary, remove/inspect the air regulator diaphragm for
cuts, tears, or abrasions.
Inspect the diaphragm seat and rail for damage. If the air
regulator is faulty, replace the port fuel rail.
Damaged valve. Replace the valve with an Air Valve Kit.
Remove/inspect the tracker valve diaphragm for cuts, tears, or
abrasions.
Inspect the diaphragm seat and rail for damage. Replace
components as necessary.
Check the air system for fuel contamination.
Inspect the fuel hoses for blockage, kinks, or tears.
Clean, correct, or replace components as necessary.
Remove/inspect the fuel regulator diaphragm for cuts, tears, or
abrasions.
Inspect the diaphragm seat and rail for damage. If the fuel
regulator is faulty, replace the port fuel rail.
Check the air system for fuel contamination.
90-8M0050731 MAY 2011