jcb G20, Operator'S Manual

Page: 127 / 177

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