Cummins ISL Quick Sheet

The Cummins ISL engine is mostly known for being the powerhouse of the larger sized motorhomes. Although also used for firetrucks due to the high horsepower ratings, the ISL really shines when it powers the Cummins diesel motorhome.

The original ISL engine feautured a fuel pump similiar to the ISC. This pump is known as the Cummins Accumulator Pump System (CAPS). This CAPS pump was a computer controlled injection pump, with individual fuel lines to each injector.

In 2003, Cummins released the updated ISL engine. Among other differences, the most significant was the change to the High Pressure Common Rail (HPCR) fuel system. The new fuel system eliminated the CAPS injection pump, relying on electronic controlled injectors to actuate fuel.

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

Engine Ratings

Advertised hp @ rpmPeak Torquelb-ft @ rpmGovernedSpeed
350 - 4001050 - 1200 @ 13002200

Maintenance Schedule (CAPS Fuel System)
(Why Fleetguard Filters?)
Oil Filter18,000 Miles, 500 Hours, or 6 Months
Fuel Filter18,000 Miles, 500 Hours, or 6 Months
Coolant Filter18,000 Miles, 500 Hours, or 6 Months
Valve Adjustment150,000 Miles, 5000 Hours, or 4 Years


Maintenance Schedule (HPCR Fuel System)
(Why Fleetguard Filters?)
Oil Filter20,000 Miles, 500 Hours, or 6 Months
Fuel Filter20,000 Miles, 500 Hours, or 6 Months
Coolant Filter20,000 Miles, 500 Hours, or 6 Months
Valve Adjustment150,000 Miles, 5000 Hours, or 4 Years


Filter Part Numbers (Fleetguard Numbers)
HPCR (03 & up)CAPS (98-03)
Oil FilterLF9009LF9009
Fuel Filter (Water Seperator)FS1003FS1022(without EGR),
FS1003 (with EGR)
Fuel FilterFF5488N/A


Useful Specs (CAPS or HPCR Fuel System)
Intake Valve Clearance.012"
Exhaust Valve Clearance.022"
Engine Brake Clearance.090"
Firing Order1-5-3-6-2-4
Oil Pressure10psi (Idle), 30psi (Rated RPM)

Fuel Pressure Specs (Minimum, CAPS & HPCR)

Lift Pump5 psi cranking
Gear Pump10 psi Cranking
70 psi @ rated speed


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