Dover HEIL Command-SST - CNG Fuel System Troubleshooting (Continued)

Issued June 2020
Compressed Natural Gas (CNG) Option
Copyright 2020, Heil Environmental
Printed in U.S.A.
233
CNG FUEL SYSTEM TROUBLESHOOTING (CONTINUED)
The following table lists possible problems, along with causes, corrections, and results.
PROBLEM OBSERVED
POSSIBLE CAUSES
CORRECTIVE/DIAGNOSTIC
ACTIONS
RESULTS AND OTHER
ACTIONS
Vehicle's starter operates
but the vehicle does not
run.
Fuel is not making it
through the fuel module to
the engine.
*The manual valve on the front
of the fuel module should be
set to "On".
*The fuel module high pressure
gauge should read above 5000
psi. Disconnect the 12-pin
electrical connector at the rear
of the fuel module. Use a DC
voltmeter across pins 8 (BLU)
and 9 (GRN) of the vehicle side
of the connector (male
connector). The voltage should
read:
Ignition switch "Off" 0 vdc.
Ignition switch "Run" 12 vdc.
Ignition switch "Start" 12 vdc.
*Reconnect the 12-pin
electrical connector at the rear
of the fuel module. Have an
assistant repeatedly cycle the
ignition switch between "Off"
and "Run" while listening for
the "click" of the fuel solenoid
being actuated near the
maintenance door.
*If the voltage does NOT
change as described, the
problem is most likely
located in the vehicle's
electrical signal that
actuates the fuel solenoid.
*If the voltage changes as
described and the "click" of
the fuel solenoid is
detected, the problem is
most likely an engine
control problem prohibiting
the vehicle from starting.
*If the voltage changes as
described but the "click" of
the fuel solenoid is NOT
detected then the problem
is most likely a failed
solenoid in the fuel
module.
*If the problem cannot be
resolved, call 866-310-
4345 for technical
assistance.