TRUCK SERVICE MANUAL
FUEL SYSTEM
Fuel brown in appearance.
New oil is clear in appearance and becomes amber
during use, never use when brown,
Dirty fuel.
Based on 8 hours per day, clean filter and change oil
Fuel Aerated.
monthly or after 160 hours operation.
Low oil level in tank.
It is normal for the drain on flange-type injectors to
appear "milky."
Air not completely expelled from system after filter
change or after having lines disconnected for other
The PT (type B) (type C) and PT (type D) drain should
reasons.
normally be clear. Fuel in the cup seat block-to-solenoid
line (line H, in Fig. 6-1-121)must always appear clear
Air leak between supply tank and gear pump suction.
with all injector models.
(a) Strainer cap loose or cap gasket missing.
It must be possible to disconnect the injector inlet lines
immediately after shutting off the test stand without
(b) Air leaks in strainer-to-gear pump section line or at
evidence of any compressed air in the system.
connections.
Fill tank to 3/4 or above.
Check 14 - Solenoid Valve
Without breaking fuel line connections, remove the filter
assembly from its mounting bracket. 'With the filter
Cause
assembly in inverted position and the test stand running
at low pressure, bleed the filter at the drain cock until oil
Solenoid leaking fuel into by-pass line during test cycle.
is free of air.
Improperly installed solenoid valve (incoming fuel line
Correct as required.
connected to discharge port and vial line connected to
inlet port) causing excessive restriction on metered fuel.
Correction
Solenoid valve sticks and fails to divert fuel to vials at
Check for foreign particles and pitted valve or seat and
instant counter actuating switch is depressed. The 0.035
clean, repair or replace as necessary.
inch (.89 mm) orifice below the solenoid is partially
clogged with foreign particles causing excessive
Check identification on solenoid valve inlet port to which
restriction which expands injector-to-solenoid line (line H,
line from injector cup tip must be connected is stamped
Fig. 6-1-121) while fuel is being by-passed but regains
IN. Directly opposite is discharge port which must be
normal size and empties excess fuel into vial when test
connected to vial line. Correct if necessary.
Clean valve until it operates freely or replace.
Clean as required.
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