Operation and maintenance manual

QSB4.5 and QSB6.7 Troubleshooting Symptoms Charts
Section TS - Troubleshooting Symptoms Page TS-27
Engine Power Output Low
Cause Correction
STEP 1
Electronic fault codes are active
.............
For instructions on how to read active fault codes,
refer to Section 1. If fault codes are active, contact
a Cummins Authorized Repair Facility.
OK
Go To Next Step
STEP 2
Fuel grade is not correct for the application or the
fuel quality is poor
.............
Operate the engine from a tank of high-quality fuel.
Refer to Fuel Recommendations and
Specifications in Section V.
OK
Go To Next Step
STEP 3
Engine is operating above recommended altitude
.............
Engine power decreases above recommended
altitude. Refer to the OEM's altitude operation
guidelines..
OK
Go To Next Step
STEP 4
Tachometer is not calibrated or is malfunctioning
.............
Compare the tachometer reading with a handheld
tachometer or an electronic service tool reading.
Calibrate or replace the tachometer as necessary.
Refer to the OEM service manual.
OK
Go To Next Step
STEP 5
Intake and exhaust system restricted
.............
Check the intake and exhaust systems for
restrictions. Inspect the intake air filter and replace
as necessary.
OK
Go To Next Step
STEP 6
Air intake system restriction is above specification
.............
Check the air intake system for restriction. Clean
or replace the air filter and inlet piping as
necessary. Refer to Section 4.
OK
Go To Next Step
STEP 7
Air intake or exhaust leaks
.............
Check for loose or damaged piping connections
and missing pipe plugs. Check the turbocharger
and exhaust manifold mounting. Refer to Section
4.
OK
Go To Next Step
STEP 8
Air leak between the turbocharger and the intake
manifold
.............
Check for leaks in the air crossover tube, charge
air cooler connections, hoses, or through holes in
the manifold cover and repair or replace if
necessary. Refer to the OEM service manual.
OK
Go To Next Step