High Pressure Lock-Off: Installation

2004 Oldsmobile Bravada RWDSECTION Installation
WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. To install, reverse removal procedure. Use NEW "O" rings lubricated with petroleum jelly for all applications. Tighten HPL to nominal torque of 225 ft. lbs. (305 N.m) at zero degrees. Torque wrench and HPL crowfoot must be compensated. To obtain proper dial reading, perform the following:
    • Multiply torque wrench length in inches by 305. Example for 18" torque wrench: 18 X 305 = 5490.
    • Add 3 to the length of torque wrench. Example for 18" torque wrench: 18 + 3 = 21.
    • Divide first value obtained, by second value obtained. The result will indicate amount of torque your wrench should tighten HPL to.

    Example for 18" torque wrench: 5490 divided by 21 equals 261.4. An 18" long torque wrench should tighten HPL to 193 ft. lbs. (261.4 N.m).

  2. Verify alignment of HPL inlet port. Fitting should be at the 3 o'clock position. Adjust tank as necessary. Tank should be located 10.5" (26.7 cm) from left edge of left tank strap. Adjust tank as necessary. Tighten tank strap nuts to 35 ft. lbs. (48 N.m).
  3. Tighten vent boot clamp to 18 INCH lbs. (2 N.m). Install fuel outlet fitting into HPL. Tighten fitting to 20 ft. lbs. (27 N.m). Install fuel inlet fitting into HPL. Tighten fitting to 35 ft. lbs. (48 N.m). Install FPS into HPL. Tighten fitting to 20 ft. lbs. (27 N.m). Install pressure relief device fitting into HPL. Tighten fitting to 35 ft. lbs. (48 N.m).
  4. Install pressure relief device line and HPL-to-HPR lines as an assembly. Tighten pressure relief device line fitting to 27 ft. lbs. (37 N.m). Tighten HPL-to-HPR fuel line fittings to 18 ft. lbs. (24 N.m). Install fill valve-to-union fill line. Tighten fittings to 27 ft. lbs. (37 N.m). Install union-to-HPL fill line. Tighten fittings to 27 ft. lbs. (37 N.m).
  5. CAUTION: High Pressure Lock-off (HPL) seal is more likely to leak at a lower fuel pressure. Always perform fuel leak procedure exactly as specified. Failure to follow proper procedures may result in serious injury or damage to vehicle or the part.
  6. Fill fuel tank in 3 stages as follows: 500 psi (3447 kPa), 1500 psi (10,342 kPa) and 3000 psi (20,684 kPa). Using Ultrasonic Leak Detector (J 41416), check for CNG fuel leaks at each serviced fitting. Position 4 hose clamps at vent boot, vent hose and fill valve boot. Install vent boot cover using new cover nuts. Tighten new vent boot cover nuts to 54 INCH lbs. (6 N.m). Attach information label supplied with replacement HPL in a visible location on head of tank. Install spare tire bracket and spare tire bracket bolts. Tighten spare tire bracket bolts to 20 ft. lbs. (27 N.m). Install tank cover. Tighten tank cover bolts to 15 ft. lbs. (20 N.m).
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.