Fuel Supply Maintenance Schedules

Simplex Fuel Supply Systems are designed to require minimum maintenance. All components have been chosen for a long, reliable life.


The Day Tank is constantly lubricated by the diesel fuel it transfers. Inspect this tank at least once every year for damage, leakage, or rust on both inside and outside the tank. Promptly repair or replace any significantly damaged or deteriorated Day Tank. Two basic intervals of maintenance are required:

Each Year

  1. Water and sediment should be drained from the tank each year. If normal engine/generator testing does not consume one tank full of fuel each year the tank should be drained and refilled with fresh fuel.
  2. Remove the inspection port from the Day Tank. The port is shown in the illustration below. Examine the interior of the Day Tank. Using an inspection lamp examine all internal Day Tank components. With tank drained test sending unit operation. Install a new inspection port gasket and replace the inspection port cover.
  3. Press the Press-To-Test button and observe pump and motor performance.
  4. Inspect pump/motor alignment and wear. Inspect the pump for leaks.
  5. Tighten hose clamps at pump/hose connections. Tighten the pump bracket, motor bracket, and pump/motor coupler hardware.
  6. Inspect all plumbing connections for leaks. Test all options and fuel level alarms for proper operation.
  7. Tighten all electrical connections.

After the first three years

After the first three years of normal use oil the Day Tank motor with 10 drops of 5W30 or 10W oil. Do not over oil the motor.