Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 199Get this manual
DIRECT FUEL INJECTION
FUEL PRESSURE AND AIR PRESSURE TROUBLESHOOTING CHART
PROBLEM Fuel Pressure and Air Pressure are Both Low CORRECTIVE ACTION 1Inspect air compressor air intake (air filter in flywheel cover) for blockage2Remove air compressor cylinder head and inspect for scuffing of cylinder wallInspect for broken reeds andor reed stops3Tracker Valve Remove and inspect diaphragm for cuts or tears and seat damage on diaphragm and rail4Air Regulator Remove and inspect diaphragm for cuts or tears on diaphragm and railFuel Pressure Low or Fuel Pressure Drops while Running (Air Pressure Remains Normal) 1Each time key is turned to the RUN position, both electric pumps should operate for secondsIf it they do not run, check 20 ampere fuse and wire connections2If pumps run but have no fuel output, check vapor separator (remove drain plug) for fuel3If no fuel present in vapor separator, check fuel water separator for debrisCheck crankcase mounted fuel pump for output4Check high pressure pump amperage drawNormal draw isamperes; if draw is below amperes, check fuel pump filter (base of pump) for debrisIf filter is clean, replace pumpIf amperage is above amperes, pump is defective replace pumpCheck low pressure output 6-9 psiCheck low pressure electric fuel pump amperage drawNormal draw isamperes; if draw is below ampere, check for blockage between pump inlet fitting and vapor separator tankIf ampere draw is above amperes, replace pump5Fuel Regulator Remove and inspect diaphragm for cuts or tears1Stuck check valve in fuel return hose2Debris blocking fuel regulator hole3Faulty pressure gauge Fuel and Air Pressure Higher than Normal 1Debris blocking air regulator passage2Air dump hose (rail to driveshaft housing) blockedplugged