Tennant 7400, Service Manual

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ENGINE--GAS/LP
6-27
7400 MM428 (3--02)
FORD DISTRIBUTORLESS IGNITION SYSTEM
SYNOPSIS
This is a troubleshooting guide for the Ford
Distributorless Ignition System.
Unlike a conventional system, the Ford
Distributorless Ignition System (DIS) uses two
coils that each fire one pair of spark plugs. The
spark plugs are also fired on both the power and
exhaust stroke.
The DIS system also uses a Universal Electronic
Spark Control (UESC) module which adjusts the
timing of the engine. The degree of timing change
needed is determined by electrical and vacuum
input to the UESC, these are:
The engine harness has a separate wire for the
gas and another for the LPG machines. Make
sure you connect the correct wire for the type of
fuel being used.
ENGINE LOAD -- FROM PRESSURE
REDUCER:
Located in the intake manifold.
Minimum 21 KPA (6.22” Hg)
Maximum 101 KPA (29.91” Hg)
ENGINE TEMPERATURE
The Engine Coolant Temperature Sensor (ECTS)
located in the intake manifold water jacket sends
engine temperature information to UESC.
Minimum --39
_
C 38
_
F
Maximum 112
_
C 232
_
F
When the engine is starting, at 250 RPM or less,
the timing is set at 10
_
before top dead center
(BTDC).