Cummins ISB Quick Sheet

Although the Cummins ISB is recognized mostly as the powerplant for the Dodge Cummins diesel, the engine is also used in many motorhome and industrial applications.

Known sometimes as the " 5.9 Cummins ", The Cummins ISB was first introduced in late 1998. Originally the engine was equipped with a Bosch VP44 rotary injection pump, but was changed for 2003 to a high pressure common rail (HPCR) fuel system.

Although a reliable engine, the VP44 injection pump was known to cause problems. The pump is very sensitive to lack of fuel lift pump pressure, and quite costly to repair. If your lift pump pressure dropped too low (or quit all together), it was not long before your injection pump would start logging faults. There was no way to know if the lift pump had failed without a manual pressure gauge. Later, lift pump kits became available to add a "dummy" light to the system which would illuminate if the pressure dropped below 3.5 psi.

The ISB engine is still used in many areas, although the 5.9 Cummins can now be replaced by the 6.7 Cummins.

Use the charts below for useful information for the ISB engine:

Engine Ratings

Advertised hp @ rpmPeak Torquelb-ft @ rpmGovernedSpeed
235 - 325 @ 2900460 - 610 @ 16002900

Maintenance Schedule(Why Fleetguard Filters?)
Oil Filter7,500 Miles
Fuel Filter15,000 Miles
Valve Adjustment150,000 Miles


"Common Rail" Filter Part Numbers (Fleetguard Numbers)
With EGRWithout EGR
Oil FilterLF3970LF16015
Fuel FilterFS19596FF5485

"VP44" Filter Part Numbers (Fleetguard Numbers)
Oil FilterLF3970
Fuel FilterFS1261 (Spin On)or FS19519 (Cartridge)



Useful Specs "Common Rail"
Intake Valve Clearance.010"
Exhaust Valve Clearance.020"
Firing Order1-5-3-6-2-4
Oil Pressure10psi (Idle), 30psi (Rated RPM)

Useful Specs "VP44"
Intake Valve Clearance.010"
Exhaust Valve Clearance.020"
Firing Order1-5-3-6-2-4
Oil Pressure15psi (Idle), 45psi (Rated RPM)
Lift Pump Pressure8-17 psi (before filter)


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