Skip to main content

Warning for Common-Rail Fuel Systems

  • Author:
  • Updated:

Installing a Diesel Priming System on Your Boat

Story and photography by Capt. Vincent Daniello

Warning for Common-Rail Fuel Systems

New common-rail engine fuel pressure is so high it can literally slice skin like a scalpel. While you should never attempt to bleed anything past the secondary fuel filter on a common-rail diesel, you really shouldn’t have to. Such engines typically bleed themselves. With the new Cummins’ B-series engines, for example, just turn the key. The engine’s electric fuel pump draws fuel and purges air through the Racor fuel filter, secondary filters, and the entire fuel system.

Some common-rail engines do have to be bled through the secondary fuel filter, however. Even with a Reverso Fuel Primer installed, you’ll have to crack bleed screws to release air, since common-rail engines return very little or, more typically, no fuel at all to the tank.

One more warning: Never fill common-rail secondary filters from a jug of diesel after installing a new element—just a bit of contamination in that jug sneaking past the element may cost tens of thousands of dollars for repairs. That advice, by the way, holds for most modern diesels, common-rail or not.