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Cummins QSB5.9 engine does not start

ElOde

New member
I have a QSB5.9 cummins engine,it was working perfectly. After several starts and stops, now the engine does not want to start and has a sound alarm.
Anyone know what can it be?
 
It can be a lot of things but my first check would be the fuel filters and to reprime the fuel system. After that you could be looking at lots if different sensors but a complete no start rather than poor running would make me check the crank angle sensor as one of the first thoughts.
 
Hi. Thanks for your help, I will start the diagnosis by that sensor,I was looking for the wiring diagram of cummins QSB 5.9 but I only got the cummins ISX, is it the same?
Thanks for everything
 
Good morning, please someone can tell me where to find, the following documents: QSB 5.9 CM850 Smarcrft 2.x Wiring Diagram

Thank You..
 
Hello, have you solved you problem? If diesel generators fail to start, you can analyze the causes from fuel system failure, electric starting system failure, insufficient compression pressure in the cylinder and the low ambient temperature and other factors.

1. Air in the fuel system
This is a common problem that a diesel generator fails to start normally.
Solution: Check whether the fuel oil pipe connector is loose or not, and ensure that the air is cleared from the fuel system. Loosen the bleed screw bolt on the diesel filter, and then use the manual oil pump to pump the fuel until the air bubble is gone.
2. Fuel Line Obstruction
Solution: Check whether the pipeline is smooth or not.
3. Fuel Filter Clogging
Solution: Clean the filter or replace the filter element
4. The Handle Position of Fuel Injection Pump Is Not Correct
Solution: The handle position should be pushed to no-load when starting the diesel generator set. Rotation speed is about 700-900r/min.
5. Fuel Injector Problem – Little fuel injection or fuel injection is not atomized
Solution: Remove the fuel injector, connect it to the high pressure oil pump, pry the fuel injection pump plunger spring and observe the spray condition. If necessary, wash the injection pump.
6. Oil Supply Problem – Oil transfer pump doesn’t supply oil or the oil supply is brokenly.
Solution: Check whether the oil inlet pipe is leaked or not and the filter screen on the oil inlet pipe connector is blocked or not.

Electric Starting System Failure


1. Battery Power Shortage
The most common failure for diesel generator is battery failure.
Solution: Use the battery with sufficient power, or increase the battery to use in parallel. Replace the new start-up battery if necessary.
2. Circuit Wiring Error or Poor Contact
Solution: Check whether the wiring is correct and reliable.

The compression pressure in the cylinder is insufficient; fuel injection is normal but does not catch fire; or fuel oil inside the exhaust pipe

1. Excessive wear of piston ring and cylinder liner
Solution: Replace the piston ring, and replace the cylinder liner according to the wear condition.
2. Valve leakage
Solution: Check the valve clearance, vlave spring, as well as the sealing of the valve guide and seat. If the seal is not good, you should make a repair.
3. Combustion chamber volume is too large
Solution: Check whether the piston belongs to the model, if necessary, measure the combustion chamber volume.

Genset repair.jpg
 
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