Hummer H1 Service Manual page 45

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2-8 Engine
PROBLEM
Hard Starting 1. InsufÞcient cranking speed (below 100 rpm
2. Starter problem
3. InsufÞcient fuel to injectors, or start switch
4. Water in fuel (Þlter indicator light NOT on).
5. Glow plugs inoperative (most noticeable at
6. Air in fuel delivery lines.
7. Fuel return lines restricted or tank vent inop-
8. Air cleaner plugged (after extended off-road
9. Injection pump timing or camshaft timing
10. Vehicle misfueled.
POTENTIAL CAUSE
cold or 180 rpm hot).
Caused by:
¥ Low batteries
¥ Bad cable connections
¥ Serpentine belt or alternator problem
¥ Poor connections
¥ Relay
¥ Solenoid
¥ Brushes
¥ Armature
¥ Starter drive damage
has fault. Check run solenoid also.
cold ambient temperatures).
erative.
operation).
may be off if pump, cam, or timing chain/
sprockets/gears were removed/replaced dur-
ing service.
Engine Diagnosis
1. Check, repair cables or connections. Recharge bat-
teries if low. Replace batteries if shorted, sul-
phated, damaged. Replace belt or tensioner if
damaged. Test alternator output and repair or
replace if low.
2. Check/repair cable and solenoid connections if
needed. Check starter draw; overhaul if draw
exceeds 450-475 amps.
Remove and overhaul starter if brushes, starter
drive, or armature are faulty.
3. Check fuel volume at supply pump and injectors
while cranking engine. If volume is low, check for
restrictions in lines or at Þlter. If volume is OK,
check pressure at pumps and injectors and repair
as needed.
4. Drain off water at fuel Þlter draincock. Then crank
engine with draincock open for 5-10 seconds to
purge remaining water. If water continues to
appear in fuel coming out draincock, purge fuel
tank and lines, and refuel vehicle.
5. Check fuse and wiring harness to plugs. Correct
open or short as required. Refer to diagnosis in
Section 12 if required.
6. Check for loose fuel line connections at pump and
injectors. Correct if necessary then bleed any
remaining air at injectors.
7. Check return lines (from engine to tank) and cor-
rect restrictions, kinks, plugged lines. Make sure
tank vent is OK. Repair as necessary.
8. Remove and clean air intake components. Replace
Þlter element if plugged or restricted.
9. Check timing marks on pump and front cover. If
aligned, check marks on pump gears and cam
sprockets. Re-time if necessary.
10. Drain sample at Þlter draincock. Replace fuel load
if fuel contains gasoline, kerosene, fuel oil, or low
quality fuel.
CORRECTION
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