On the FASS track

Updated Apr 10, 2015

Big Red gets F.A.S.S. fuel system

Upgrading to a premium  fuel-air separation system improves overall performance on our Project GMC 3500HD’s Duramax


by Bruce W. Smith


Adding power and fuel economy are always high on diesel pickup owner’s wish list. But one performance area many overlook toward those two goals is the most obvious: fuel delivery.

Diesel pickup fuel tanks are mounted at least two feet below and ten feet away from the engine-mounted fuel pump. This configuration creates multiple problems associated with the fuel delivery to the engine.

First, the injection pump has to draw the fuel from the tank by creating a vacuum, a process that  produces fuel vapor.

Second, while the truck is in motion the movement of the fuel inside the tank causes air to be pulled along in the fuel stream.

F.A.S.S. system purges air and contaminants from the fuel for better diesel power and fuel economy.

“By having entrained air and air vapor in the fuel, the engine does not perform at the manufacturer’s specification, and the fuel injectors and fuel injection pump are not properly lubricated,” says F.A.S.S. Systems‘ Brad Ekstam.

“Air and fuel vapor occupy the space that should have pure fuel, thus delaying the injection of fuel (retarded timing) into the combustion chamber.

“The air/vapor present in fuel is very inconsistent, making it virtually impossible to adapt the varying degrees of changes in injection timing.”

Ekstam says this inconsistency in the fuel hurts both power and fuel economy.

Air in the fuel has also been linked to these engine symptoms:

  • Low Horsepower
  • Low Fuel Mileage/Poor Fuel Mileage
  • Excessive Smoke
  • Injector Failure
  • Hard Start or Will Not Start
  • Engine Surges at Low Idle
  • Warm Engine Runs Rough or Misfires in Operating Range
  • Rough Idle
  • Engine Will Not Reach Rated Speed When Loaded

So, to make sure Big Red’s 6.6L Duramax has the best fuel and fuel delivery possible, we had Truck Supply & Outfitter’s Daniel Parker install a F.A.S.S. 95 (95gph) fuel pump/filter kit ($600) while upgrading Big Red’s stock fuel tank to a higher capacity version from Transfer Flow.

Installation is easy for any qualified diesel mechanic and should take less than two hours.

Now Big Red is literally on the F.A.S.S. track to better power and mpg.