Case Study: Diesel Ram 3500 lacks power under load after repairs

Sept. 1, 2022

The owner of this Dodge Ram brought the truck in because the engine would start and run for about a minute, then stall.

Related To:

Vehicle: 2001 Dodge RAM 3500, 4WD, L6-5.9L DSL Turbo, VIN 7, Automatic Transmission/Transaxle

Mileage: 172,556

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 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.

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!

Reprinted with permission from ALLDATA.

About the Author

Richard Diegle | Senior Automotive Editor for ALLDATA

Rich Diegle has been in the automotive industry since 1978. After graduating from a local community college, he began working at a Nissan dealership as a used car technician. Since then, he’s worked as a Nissan and ASE master automotive technician, shop owner, marketing copywriter, automotive editor, public relations manager, instructor, ALLDATA Tech-Assist team manager, and a senior automotive editor.