Emissions - EVAP Leak Code Diagnosis/Repair

Group
30 - FUEL SYSTEM

Number
02-30-001

Date
12-2002

Model
All Models

Subject:
ENHANCED EVAPORATIVE EMISSION CONTROL DIAGNOSIS AND REPAIR FOR P0442, P0446, P0455 AND P1443 LEAK CODES USING A LOW PRESSURE GAUGE

DESCRIPTION:

This TSB is an addendum to TSB 00-30-003. Technicians already familiar with TSB 00-30-003 will benefit from the new diagnostic tree. Several revisions are embedded into the diagnostic tree, and a summary of the revisions are shown. New technicians can start with the diagnostic tree and refer to TSB 00-30-003 for additional information.

INTRODUCTION:

By pressurizing a sealed evaporative emission system, the pressure leakdown rate can easily be measured using a low pressure gauge. The system should be slowly pressurized to a very low pressure (in this case 20" H20) . A properly operating system (one that does not leak) will not lose any pressure; in fact, with high fuel temperature and high ambient temperature, pressure may increase due to fuel vaporization. A very small leak is read as a 2" H20 drop of pressure over one minute.This tool is intended to verify and diagnose evaporative emission leaks with Diagnostic Trouble Codes (DTCs) P0456, P0442, P0455, P0457, and P1443. In some instances DTCs P0446, P0440 and P0441 can also be diagnosed.

Low Pressure Gauge Tool (L.P.G.T.) - SPX EVAP Tester P/N J-44680 Tips for using the low pressure gauge.

1. Pressurize evap system to 20" H20 for testing.

2. Never use shop air, or pressurize beyond 30" H20.

3. Always use teflon tape or sealer on the hose barb connection.

4. Use a hose clamp over the connection hose.

5. Use hose pinching pliers to clamp off sections to isolate the leak.

6. Use a bungee cord (or equivalent) to support the tool to prevent kinked hoses.

Summary of revisions from TSB 00-30-003:

1. Fuel caps must NOT be tightened or adjusted prior to performing the leak check.

A. Fuel caps that are loose due to improper installation by the customer are not warrantable. A loose fuel cap is not a result of a "defect in factory material or workmanship".

2. Fuel level must be below 1/4 to perform the low pressure leak check. The ideal condition is with low fuel light on.

3. The pressure tester tool should be pinched with hose pinching pliers (such as Snap-on P/N BLC2 or equivalent) between the one way valve and the pressure release valve.

4. Pipe thread sealer must be used on the hose barb connection of the pressure gauge.

5. Canister close valve or DM-TL replacement should only be performed after proper pressure checking.