1992 GMC Suburban 1/2 Ton 2WD V8-350 5.7LFACTORY OEM SERVICE PROCEDURE

Vapor Pipe Repair

NOTE:

a. The vapor pipe is secured to the underbody with clamp and screw assemblies. Flexible hoses are connected at the fuel tank and the fuel vapor canister. The pipe should be inspected occasionally for leaks, kinks, or dents and repaired as required.

b. Repair vapor pipe in sections using brazed seamless tubing meeting GM specification 123M or its equivalent or hose identified with the word "Flouroelastomer". Hose NOT so marked could cause failure or failure to meet emission standard.

^ DO NOT use copper or aluminium tubing to replace steel tubing. Those materials DO NOT have satisfactory durability to withstand normal vehicle vibrations.

^ DO NOT use rubber hose within 100 mm (4") of any part of the exhaust system or within 250 mm (10") of the catalytic converter. Hose inside diameter must match steel tubing outside diameter.

Procedure:

1. In repairable areas, cut a piece of fuel hose 100 mm (4") longer than the portion of the line being removed.
When more than a 150 mm (6") length of pipe is removed, use a combination of steel tubing and hose so that the entire hose length will NOT be more than 250 mm (10").

2. Cut the ends of the pipe remaining on the vehicle square by using a tubing cutter. By using the first step of a double flaring tool, form a bead on the ends of both pipe sections. If the pipe is too corroded to withstand bead operation without damage, the pipe should be replaced. If a new section of pipe is used, form a bead on both ends.

3. Use a screw type hose clamp. Slide clamps onto pipe and push hose 50 mm (2") onto each portion of fuel pipe. Tighten clamps on each side of repair.
Factory Service Tools

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When to See a Mechanic

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

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

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