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2.8.2 Fuel Supply Connection by Tapping the fuel Rail

NOTE: If your vehicle’s fuel rail is not equipped with a test port, the fuel rail will need to be removed
and tapped for the 1/16” NPT x 4AN fitting (22) using the steps A through F on the following page.

CAUTION! Before attempting any modification to the fuel rail, make sure that enough wall thickness is
available to achieve 3 to 4 threads of engagement during the tapping operation. This would be
equivalent to .120” (3.00mm) to .150” (4.00mm) wall thickness.

FIG. 6

A. Select a location for the 1/16” NPT x 4AN fitting (22) on the fuel rail. Make sure that
the fitting and line are clear of all engine components.
B. Remove the fuel rail from the engine. Remove the fuel injectors and regulator (if
applicable) from the fuel rail. Drill a ¼” hole in the fuel rail, making sure that the
hole is perpendicular to the mounting surface, and that the hole penetrates into the
fuel rail reservoir.
C. Tap the ¼” hole with the 1/16” tap (25). De-Burr entry and exit holes.
CAUTION! Remove all debris in the fuel rail or engine damage could occur.
D. Install the 1/16” NPT x 4AN fitting (22) in the tapped hole. Use Teflon paste to
avoid fuel leaks.
E. Clean debris out of the fuel rail once again just to be safe.
F. Re-install the fuel rail injectors and regulator. Use clean engine oil to lubricate the
injector o-rings.
G. Install the fuel rail onto the engine.

4) Thread the remaining end of the 4AN hose (21) to the test port/4AN fitting.

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