Continuous flow fuel injections systems

Continuous Flow Fuel Injection Systems

By Randy Knuteson

November 1998

ontinental Motors calls it their "Continuous Flow Fuel Injection System." Some technicians refer to it in less dignified terms, replete with colorful expletives. The proclivity of human nature has always been to focus on the negative. But regardless of an occasional negative encounter, the positive attributes of these systems are easy to identify. You need not look far to appreciate the commendable features of the TCM Fuel Injection System. For many years, the factory has pointed to "simplicity" as being the "single-most significant feature" of their systems. Some would concur. Others would strongly disagree. The goal of this article is to provide some information to clear up any misunderstandings that may have landed you in the "disagree" camp.

Continuous Flow Fuel Injection Systems

By Randy Knuteson

November 1998

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Setting up the System
Is "Fine-Tuning" Required?
Some shops make the erroneous assumption that a freshly overhauled fuel system need only to be bolted to the engine and flown away. They say "after all, wasn't the system overhauled and calibrated to factory specs?" Yes — however, variations in induction systems, supply systems, and operating environments mandate a final "tweaking" of the installed components. Still, some tenaciously hold to the mind set that "it should be set up for my airplane out of the box."

For this reason, many Repair Stations have difficulty persuading technicians to use calibrated hand-held gauges while setting up their Continental systems on the airframe. While TCM strongly recommends the usage of externally plumbed gauges, some technicians still consider this procedure nothing more than a mere suggestion. Failure to follow this "suggestion" often results in lackluster performance, frustration, and dissatisfied customers. Always use these gauges if you expect to appreciate the system's full-performance capabilities. Teledyne's Service Information Directive 97-3 provides clear instructions for final adjustments once fuel components are installed on the airplane.

Before Adjusting
Verify the accuracy of the following gauges before making adjustments to the fuel system: Tach, MAP, Fuel Flow, Oil Temp, Oil Press, CHT, EGT. Don't rely solely on the ship's gauges when setting pressures and flows. Rectify any discrepancy if fou nd. Errant gauge readings, if significant, can result in annealed rings, compression loss, and cylinder detonation. Tee in the calibrated gauges. Pressurize the system with the boost pump and inspect for leaks. Chock the wheels, set the brakes. Finally, before attempting any adjustments, allow CHTs and oil temps to reach their normal operating values as spelled out in the POH.

Cautionary Notes
Be sure to limit the duration of full rated power run-ups, and cowl the engine to direct prop-blast across the cooling fins of the cylinders. Carefully monitor CHT readings during all ground runs. Allow the engine to stabilize for 10 to 15 seconds, and take your readings, but always hold high rpm runs to a minimum especially with newly installed cylinders. Never exceed 420ûF CHT or 210ûF oil temps. Failure to take these precautions could dramatically shorten the life of your cylinders. After full powered runs, it is also imperative that the engine be allowed to run at 800 to 1000 rpm for a few minutes. This practice allows the engine temperatures to stabilize prior to engine shut down.