If a high-pressu re lin e con nection is leakin g, coun-
terh old a nd tight en the con nection t o specification
then perform this procedu re again (Refer to 14 -
FUE L SYSTEM - STANDARD PROCE DURE ).
Replace an y damaged, restr icted or leaking high -
pr essu re fu el lines with t he cor rect replacem ent
line .
CAUTION: The high-pressure fuel lines cannot con-
tact each other or other components. Do not
attempt to weld high-pressure fuel lines or to repair
lines that are damaged. Only use the recommended
lines when replacement of high-pressure fuel line is
necessary.
DIAGNOSIS AND TESTING - AIR IN FUEL SYS-
TEM
Air will en ter the fuel syst em whenever fuel supply
lin es, sepa rat or filters, injection pum p, high-pressur e
lin es or injectors a re removed or discon nected. Air
trapped in t he fuel syst em can result in hard sta rt-
ing, a rough r unning engine, engine misfire, low
power, excessive smoke an d fu el knock.
In spect the fuel system fr om the fuel tan k to th e
injector s for loose conn ection s (Refer to 14 - FUEL
SYSTEM - WARNING). Leaking fu el is an indicator
of loose connect ions or defective seals. Air can also
enter the fuel system between th e fuel ta nk and th e
fuel pu mp. Inspect the fuel tank m odu le an d fu el
lin es for dam age t hat might a llow air int o th e sys-
tem.
With t he DRBIII! connect ed to t he vehicle, select
Engine and the select Sensor Display. Page down t o
view F uel Pr essure Set Point a nd Act ual F uel Pr es-
su re. Star t the engine and observe t he Fuel P ressure
Set Point and t he Actua l Fuel Pressure. If th e Actual
Fuel Pressure Oscillates above and below t he Fuel
Pressur e Set Point in a regular cycle, inspect th e fuel
system for air intrusion.
If the Actual Fuel Pressure gradually drops below
the Fuel Pressu re Set Point t hen spikes well above
the F uel Pressure Set Point, repla ce the fuel pr es-
su re solen iod (Refer t o 14 - FUEL SYSTEM/F UEL
INJ ECTION/FUEL P RESSURE SOLE NOID -
REMOVAL), a nd rech eck.
DIAGNOSIS AND TESTING - INJECTOR LEAK
QUANTITY
WARNING: REVIEW THE HIGH PRESSURE FUEL
SYSTEM WARNING BEFORE BEGINNING SERVICE
(Refer to 14 - FUEL SYSTEM - WARNING).
CRANKING TEST
NOTE: If an injector is found to be out of specifica-
tion, repeat this test procedure after the injector
replacement. Hydraulic flow will take the path of
least resistance and multiple failures may be identi-
fied.
Perfor m th is test with the engine at opera ting tem -
perat ure, wh en possible. This test will assist in
determ ining a defective or inter nally leakin g in jec-
tor(s) is present by mea su ring th e amou nt of fuel
return.
(1) Turn the ignition off.
(2) Remove th e engine cover (Refer t o9-ENGINE
- REMOVAL).
(3) Disconn ect the fu el retur n hoses at th e top of
the injector s.
(4) Pinch off the fuel ret urn line at the ba njo bolt
fitting of the fuel rail.
(5) Disconn ect the fuel rail solenoid a nd camsh aft
position sen sor.
(6) In st all the t est via ls ont o t he injectors and
secure with t he return hose clips (F ig. 2).
Fig. 1 Typical Test for Leaks with Cardboard
1 - HIGH-PRESSURE LINE
2 - CARDBOARD
3 - FITTING
14 - 2 F U EL S Y S T EM VA
To Next Page
Loading...
