Advance acoustic 56514925, Service Manual

Page: 93 / 260

Engine System, Diesel 93 Service Manual – Advance 7765 / Nilfisk CR1500
Problem Cause Correction
The engine will not
start (continued).
The Murphy relay is not
sending voltage to the fuel
pump.
• Check the wiring to the Murphy relay, and from the
Murphy relay to the fuel pump (wire H) and correct
as necessary.
• Check the Murphy relay for correct function and
replace if necessary.
• Check wire 6 on the Murphy relay for connection
to ground. If wire 6 is grounded, check the oil
pressure switch, water temperature switch and
associated wiring for correct function and replace
as necessary.
The engine stops
running, check
engine light is on.
The coolant temperature is
too high.
Refer to the Engine Overheating Problems section
below.
The oil pressure has
dropped below the minimum
acceptable pressure.
Refer to the Loss of Oil Pressure Protection
section below.
Engine Overheating Problems
When the water temperature switch senses that the coolant temperature is too high, it grounds out wire 6
to the Murphy relay. After 30 seconds the Murphy relay switches off the voltage to the fuel pump to stop the
engine.
Use the checklist below as a guide to thoroughly check the engine cooling system.
• Check the coolant level in the overflow tank and radiator.
• Inspect and clean the radiator and hydraulic oil cooler.
• Check for correct operation of the belt-driven engine cooling fan (slippage).
• Check to see that the engine thermostat opens.
• Check for correct water pump operation.
• Check the engine crankcase oil level.
• Check for air trapped in the cooling system. (Refer to the Engine Coolant/Replacing Engine Coolant
section.)
• Check the water temperature switch for correct function as replace if necessary.