1998-1999 5.9 L Cummins Low Power or Poor Performance

Model(s): 1998-1999 Dodge (BR/BE) Ram Truck

Group: Vehicle Performance

Bulletin No.: 18-21-99

Date: September 3, 1999

OVERVIEW

This bulletin involves diagnostic procedure that may be used to assist the technician in the diagnosis of a low power or poor performance complaint.

SYMPTOM/CONDITION

The vehicle operator may complain of slow acceleration or a lack of power when towing or hauling moderate to heavy loads. The condition may be worse at higher altitude.

DIAGNOSIS

Interview the vehicle operator to understand under what driving conditions the above symptom occurs.

1. While inside the vehicle cab and using the Diagnostic Readout Box (DRB III), verify that the throttle is opening fully.
2. Refer to the 1999 Ram Truck Service Manual 81-370-9108 pages 14-78 to 14-80. Perform the complete FUEL TRANSFER PUMP PRESSURE TEST procedure.
3. Inspect the fuel tank rollover valve for restrictions or that the shipping cap has not been left on the end of the valve.
4. Inspect the Charge Air Cooler hoses and clamps for proper installation. Inspect all connections and clamps for looseness. Verify that no leaks are present when the engine is under boost conditions. Pay close attention to the exhaust connections.
5. While performing the following road test, verify that the turbo boost pressure is 16 psi (33 in. of Hg.) during wide open throttle (WOT) acceleration. If boost pressure is found to be less than 16 psi (33 in. of Hg.), refer to TSB 11-08-98 .
6. While road testing the vehicle in a safe area and manner, conduct an acceleration test. For vehicles equipped with an automatic transmission conduct a 0-60 mph acceleration test. For vehicles equipped with a manual transmission, conduct a 40-60 mph acceleration test in 4th gear. It may take the technician performing several acceleration tests to obtain consistent acceleration times.
7. Refer the to the acceleration reference charts. If the acceleration times, of the vehicle in question, are equal to or less than the stated times listed in the following acceleration charts, then the vehicle performance is normal and the vehicle can be returned to the vehicle owner. If the acceleration times are greater than the stated times listed in the acceleration charts, then further diagnostic testing is required.