IGNITION
90-855347R1 JANUARY 1999 Page 2A-15
DFI Troubleshooting Guide
Symptom Cause Action
1. Engine cranks but won’t
start
1.0 Lanyard stop switch in wrong
position.
Reset lanyard stop switch.
1.1 Weak battery or bad starter
motor, battery voltage drops
below 8 volts while cranking
(ECM cuts out below 8 volts)
(Fuel pump requires 9 Volts).
Replace/charge battery.
Inspect condition of starter motor.
Check condition of battery termi-
nals and cables.
1.2 Low air pressure in rail (less
than 70 psi at cranking
Inspect air system for leaks.
Inspect air filter for plugging (air
pressure measured on port rail).
Inspect air compressor reed valves
if necessary.
1.3 No fuel Check that primer bulb is firm.
Key-on engine to verify that fuel
pump runs for 2 seconds and then
turn off. Measure fuel pressure
(valve on starboard rail). Fuel pres-
sure should be 10 ± 1 psi greater
than the air pressure.
1.4 Low fuel pressure Check fuel pressure from low pres-
sure electric fuel pump (6–10 psi).
Check for fuel leaks. If fuel pres-
sure leaks down faster than air
pressure, seals on fuel pump may
be leaking. Check air system pres-
sure, see 1.2.
1.5 Sheared Flywheel Key Remove flywheel and inspect key.
1.6 Blown fuse Replace fuse. Inspect engine har-
ness and electrical components.
1.7 Main Power Relay not
functioning
Listen for relay to “click” when the
key switch is turned on.
1.8 Spark Plugs Remove fuel pump fuse.
Unplug all direct injector connec-
tors.
Remove spark plugs from each
cylinder.
Connect spark plug leads to Spark
Gap Tester 91-830230T.
Crank engine or use DDT output
load test for each ignition coil and
observe spark. If no spark is pres-
ent, replace appropriate ignition
coil. If spark is present, replace
spark plugs.
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