Dodge ram truck 3500 1996 Service Manual page 1310

1 4 - 7 6 FUEL SYSTEM BR
D E S C R I P T I O N A N D O P E R A T I O N (Continued)
FUEL SHUTDOWN SOLENOID RELAY
Voltage to operate the fuel shutdown (shut-off)
solenoid is supplied from the ignition switch and
through the fuel shutdown solenoid relay. The Pow­
ertrain Control Module (PCM) has no control over
the solenoid. The fuel shutdown solenoid relay is
located in the engine compartment near the brake
master cylinder (Fig. 14).
FUEL SHUT-OFF
FUEL HEATER SOLENOID RELAY
Fig. 14 Fuel Shutdown (Shut-Off) Solenoid Location
FUEL DRAIN MANIFOLD
Some fuel is continually vented from the fuel injec­
tion pump to cool the pump and the fuel injectors.
During injection, a small amount of fuel flows past
the injector nozzle and is not injected into the com­
bustion chamber. This fuel drains into the fuel drain
manifold (Fig. 1 5 ) . Fuel in the drain manifold is then
routed back to the fuel filter/water separator.
D I A G N O S S S AMB T E S T I N G
AIR IN FUEL SYSTEM
Air will enter the fuel system whenever fuel supply
lines, separator filters, injection pump, high-pressure
lines or injectors are removed or disconnected. Air
trapped in the fuel system can result in hard start­
ing, a rough running engine, engine misfire, low
power, excessive smoke and fuel knock. After service
is performed, air must be bled from the system
before starting the engine.
Inspect the fuel system from the fuel transfer
pump to the injectors for loose connections. Leaking
fuel is an indicator of loose connections or defective
Fig. 15 Fuel Drain Manifold—Typical
seals. Air can also enter the fuel system between the
fuel tank and the transfer pump. Inspect the fuel
tank and fuel lines for damage that might allow air
into the system.
For air bleeding, refer to the Air Bleed Procedure.
FUEL SUPPLY RESTRICTIONS
LOW-PRESSURE LINES
Fuel supply line restrictions or a defective fuel
transfer pump can cause starting problems and pre­
vent the engine from revving up. The starting prob­
lems include; low power and blue or white fog like
exhaust. Test all fuel supply lines for restrictions or
blockage. Flush or replace as necessary. Bleed the
fuel system of air once a fuel supply line has been
replaced. Refer to the Air Bleed Procedure section of
this group for procedures. Also refer to the Fuel
Transfer Pump Pressure Test section of this group for
restriction tests.
HIGH-PRESSURE LINES
Restricted (kinked or bent) high-pressure lines can
cause starting problems, poor engine performance
and black smoke from exhaust.
Examine all high-pressure lines for any damage.
Each radius on each high-pressure line must be
smooth and free of any bends or kinks.
Replace damaged, restricted or leaking high-pres­
sure fuel lines with the correct replacement line.
CAUTION: The high-pressure fuel lines must be
clamped securely in place in the holders. The lines
cannot contact each other or other components. Do
not attempt to weld high-pressure fuel lines or to
repair lines that are damaged. Only use the recom­
mended lines when replacement of high-pressure
fuel line is necessary.