jcb G20 Operator's Manual page 127

Air intake system blocked or restricted.
Fuel is aerated.
Fuel lift pump not operating correctly (fuel supply in-
adequate).
Fuel is contaminated or incorrect grade diesel fuel
used.
Fuel filter(s) blocked, fuel supply restricted.
Fuel drain return line blocked, not connected proper-
ly.
Check fuel inlet restriction.
Inlet and exhaust valve clearances set incorrectly.
Engine compression low in one or more cylinders.
Cranking speed too slow.
Electrical sensor fault.
Cause
Starting electrical circuit connections loose or corrod-
ed.
Battery charge low.
No electrical connection to starter solenoid.
Crankshaft rotation restricted.
Solenoid or starter motor fault.
Starter motor operating but not cranking.
Cause
No fuel in supply tank.
Engine starting under load.
Air intake or exhaust system blocked.
Fuel is aerated.
120
Table 24. Engine - Will Not Crank or Cranks Slowly
Table 25. Engine - Starts then Stops
9831/0650-3
Visually check the air intake for blockage or obstruc-
tion - remove as required. Check the air filter ele-
ments for signs of blocking - replace as required.
Check the fuel system for loose connections and
possible air ingress points. Rectify and bleed the fuel
system.
Check that the lift pump operates and delivers fuel to
the fuel injection pump. Check the correct electrical
wires for open or short circuits.
Stop the engine.
Replace the fuel filters. Operate the engine with a
temporary supply of the correct grade of clean fuel.
Monitor the engine performance.
WARNING: Dirty fuel will cause damage to the fuel
injection pump and injectors.
Check/replace the fuel filter(s). Check fuel lines for
restriction.
Verify that the fuel return line is not obstructed and
connected to the top of the fuel tank.
Maximum inlet restriction to fuel transfer pump must
not exceed 100 mm Hg (4 in. Hg).
Set the valve clearances to the recommended clear-
ances.
Check the engine compression.
Refer to Table 24.
Check the electrical connections at the sensors.
Remedy
Clean and tighten connections.
Check battery voltage, charge the battery or replace
as required. Make sure that the alternator is function-
ing correctly and charging the battery.
Check voltage to solenoid.
Use special tool 892/01147 (crankshaft turning tool)
to manual turn the engine and check for any severe
rotational resistance.
Replace starter motor.
Remove the starter motor and check for broken teeth
on the ring gear or broken starter motor spring.
Remedy
Check the level in the fuel tank, use sight gauge or
dipstick. Replenish as required.
Check for added loading from malfunctioning acces-
sories or driven units (alternator)
Visually check the air intake and exhaust system for
blockage or obstruction - remove as required. Check
the air filter elements for signs of blocking - replace
as required.
Check the fuel system for loose connections and
possible air ingress points. Rectify and bleed the fuel
system.
Maintenance
Fault-Finding
120