182 5 HARD START AND NO START DIAGNOSTICS
Figure 215 Fuel/Oil Pressure Test C oupler
NOTE: If the engine is equipped with a diagnostic
coupling, adapt the Fuel/Oil Pressure Test Coupler to
the Fuel Pressure Gauge.
Figure 216 Fuel Pressure Gauge to fuel pressure
test adapter
2. Connect Fuel Pressure Gauge with shut-off valve
and clear 3/8” diameter hose to test valve.
3. Route the clear hose into a drain pan.
WARNING: To avoid serious personal
injury, possible death or damage to the engine
or vehicle – comply with the following:
When routing test line, do not crimp the line,
run the line too close to moving parts, or let
the line touch hot engine surfaces.
4. Start or crank the engine for 20 seconds. Measure
the fuel pressure with the shut-off valve closed.
Open the shut-off valve to check for aeration.
NOTE: Breaking any fuel system joint will induce
air into the fuel system. The air should p ass in a
short period of time. As fuel pressure is relieved, a
steady stream of fuel without air bubbles indicates
the fuel is not aerated.
NOTE: If a Fuel Pressure Gauge with shut-off
valve and clear 3/8” diameter hose is not
available to check for aeration, see alternative
test “Checking for Aerated Fuel using Spare Fuel
Line.”
5. Record results on Diagnostic Form.
• If fuel pressure is below specification and fuel
is not aerated, replace the fuel filter and clean
the strainer. Test the fuel pressure again.
• If fuel is aerated, see “Aerated Fuel” in
Section 4.
• If fuel pressure is still low and fuel is not
aerated after replacing the fuel filter and
cleaning the strainer, do “Operation of the
Fuel Pump Test.”
• If fuel pressure is in specification and the fuel
is not aerated, do not continue testing the fuel
system. Continue to the next diagnostic test.
Possible Caus es
No fuel
• Low fuel level in fuel tank
• Debris in tank can cause high-restriction and low
fuel pressure.
• Inline fuel valve (if equipped) could be shut-off
• Failed seals or fuel lines between fuel tanks
• Ice in fuel lines
• Inoperative fuel tank transfer pump
• Fuel tank pickup tube cracked
Low fuel pressure
•Dirtyfilter element
• Debris o r rust in fuel strainer
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any proced ures.
Follow all warnings, cautions, and notes.
©August 2008 Navistar, Inc.
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