Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 347 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING - 3.8L)FUEL SYSTEMSFUEL INJECTOR CLEANINGCLEANING PROCEDURE
1998 Chevrolet Suburban K2500, 7.4 J, Part Time
Cleaning Procedure
1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Cleaning Procedure
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- Obtain Fuel Injector Cleaner (J 38500-A), or equivalent. Ensure shut-off valve at bottom of the canister is closed. See Fig 1.
- For US dealers, empty 2 pre-measured GM Top-Engine Cleaner containers, 0.812 oz. (24 ml) each (GM P/N 12346535), into the fuel injector cleaner.
- For Canadian dealers, measure and dispense 1.62 oz. (48 ml) of Top-Engine Cleaner (Canadian P/N 992872), into the fuel injector cleaner.
- If you are using any other brand of tank you will need a total of 3.24 oz. (960 ml) of Top-Engine Cleaner mixed with 29.16 oz. (864 ml) of regular unleaded gasoline.
- Fill the injector cleaning tank with regular unleaded gasoline. Be sure to follow all additional instructions provided with the tool.
- Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch harness connector, if equipped.
- Disconnect the fuel feed and return lines at the fuel rail. Plug the fuel feed and return lines coming off the fuel rail using Fuel Line Shut-Off Adapters (J 37287), or 3/8 Fuel Line Shut-Off Adapter (J 42964-1), and 5/16 Fuel Line Shut-Off Adapter (J 42964-2), or 3/8 Fuel Line Shut-Off Adapter (J 42873-1) and 5/16 Fuel Line Shut-Off Adapter (J 42873-2) as appropriate for the fuel system.
- Connect the fuel injector cleaner to the vehicle's fuel rail.
- Pressurize the fuel injector cleaner to 75 psi (510 kPa).
- Start and idle the engine until it stalls, due to lack of fuel. This should take about 15-20 minutes.
- Disconnect fuel injector cleaner from the fuel rail.
- Reconnect the vehicle's fuel pump relay and oil pressure switch harness connector, if equipped.
- Remove Fuel Line Shut-Off Adapters and reconnect the vehicles fuel feed and return lines.
- Start and idle the engine for an additional 2 minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.
- Repeat steps 1-5 of the appropriate Injector Balance Test and record the fuel pressure drop from each injector. See FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOLĀ or FUEL INJECTOR BALANCE TEST WITH TECH 2Ā®Ā .
- Subtract the lowest fuel pressure drop from the highest fuel pressure drop. If the value is 2 psi (15 kPa) or less, no additional action is required. If the value is greater than 2 psi (15 kPa), replace the injector with the lowest fuel pressure drop.
- Add one ounce of Port Fuel Injector Cleaner, (GM P/N 12345104, Canadian P/N 10953467), to the vehicles fuel tank for each gallon of gasoline estimated to be in the fuel tank. Instruct the customer to add the remainder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill-up.
- Advise the customer to change brands of fuel and to add GM Port Fuel Injector Cleaner every 3000 miles. GM Port Fuel Injector Cleaner contains the same additives that the fuel companies are removing from the fuel to reduce costs. Regular use of GM Port Fuel Injector Cleaner should keep the customer from having to repeat the injector cleaning procedure.
- Road test the vehicle to verify that the customer concern has been corrected.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- ā¢ You smell fuel, burning insulation, or see smoke.
- ā¢ Brakes feel soft, pull hard to one side, or make grinding noises.
- ā¢ The engine overheats, stalls repeatedly, or misfires under load.
- ā¢ You are missing required tools, torque specs, or safe lifting equipment.
- ā¢ You are not confident in the next step or safety outcome.