Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 76Get this manual
Fuel System Troubleshooting General Information
Problems, that are thought to be caused by the fuel system, may bein reality, something completel differentItems, that are show in the list on the rightcould give the impression that there is problem in the fuel system
To diagnose the fuel systemsee he "Trouble Chart", below
Propeller Spark plugs Ignition timing Ignition spark voltage Cylinder compression Reed valves
Trouble Chart
PROBLEM: Engine Turns Over but Will Not Start or Starts Hard When Cold
Possible Cause Improper starting procedure used Fuel lank empty or 100 low, improperly mixed fuel, Contaminants (water, dirtetc) in fuelCorrective Action