TECH TIP: Diesel Ram 3500 Lacks Power Under Load After Repairs
TECH TIP (courtesy from ALLDATA)
Vehicle: 2001 Dodge RAM 3500, 4WD, L6-5.9L DSL Turbo, VIN 7, Automatic Transmission/Transaxle
Problem: The owner of this Dodge Ram brought the truck in because the engine would start and run for about a minute, then stall.
Case Details: The technician found the following diagnostic trouble codes (DTCs):
- P0370 – Timing Reference High-Resolution Signal A Malfunction
- P1691 – Fuel Injection Pump Controller Calibration Error
The technician decided to replace the fuel injection pump (VP44) and clear the DTCs. With a new fuel injection pump in place, the engine idled smoothly and would run without stalling. However, it stumbled and lacked power under load.
An ALLDATA Tech-Assist consultant suggested checking the transfer pump for operation. He advised that, if the rail-mounted transfer pump failed or was weak, it could have damaged (fuel-starved) the old VP44 fuel pump. The consultant also said that if the technician was going to replace the transfer pump, Chrysler/Mopar had an updated in-tank fuel pump and provided this link: https://www.moparpartsunlimited.com/v-2001-dodge-ram-2500–base–5-9l-l6-diesel/fuel–fuel-pump-and-sending-unit
The technician found that the transfer pump fuel pressure was weak and far below specifications.
Confirmed Repair: He removed the transfer pump and installed Mopar’s updated in-tank fuel pump and fuel line kit. The technician cleared the DTCs and went for a test drive. The engine ran strong. No DTCs returned. Fixed!