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How to Solve Diesel Generator Fuel and Engine Oil Mix Up Problem

Oct. 13, 2018

Treatment of Cummins Generator set after mixing fuel and Oil

The fuel and oil of the Cummins generator set have completely different functions. They can not be mixed. Once the fuel and oil are mixed, there is a problem with the seal of the generator set, which happens from time to time in use. Below is the Cummins generator set fuel and oil after the treatment of mixed.


How to Solve Diesel Generator Fuel and Engine Oil Mix Up Problem.jpg

1. Pump membrane rot or degumming, so that diesel oil into the oil tank and oil mixing. When the oil pump is removed and the pressure is added to the oil inlet and outlet pipes on the oil pump test bench, if no leakage of diesel oil is found, the pump is in good condition.


2. The injector has low opening pressure and poor atomization, which causes diesel oil to flow into the oil pan and oil along the cylinder wall. Remove the injector and test it on a high-pressure oil pump test rig. If the injector fuel injection pressure meets the requirements, atomization is good, indicating that the injector is in good condition, otherwise, it will be repaired or replaced.


3. The oil seal of the front end of the fuel injection pump is invalid, and the check hole cover of the gear chamber cover is removed. If a large quantity of diesel fuel is ejected from behind the driver gear of the fuel injection pump. When the fuel injection pump is removed and tested on the test stand of high pressure oil pump, it is found that the oil seal at the front gear journal of many fuel injection pumps is deformed, a large amount of diesel oil is leaking, and when the oil seal seat has the disassembly gear, The marks (indentation) of the screw top by special tool deform the oil seal and seal, causing the leakage of diesel oil, finally replacing the fuel injection pump, the trouble can be dealt with.


Method for replacement of oil and fuel filters for Cummins generator sets


Since the filter will become dirty or even clogged when used for a certain period of time, oil and fuel filters should be replaced regularly. The methods and procedures for replacing oil and fuel filters for Cummins generator set are as follow:


Since the filter will become dirty or even clogged when used for a certain period of time, oil and fuel filters should be replaced regularly. The methods and procedures for replacing the oil and fuel filters of the Cummins generator set are as follows:


1. Remove the blocked filter from the diesel engine and throw it away. Rotary filter wrench can be used when disassembling.


2. Add the specified lubricating oil (fuel or diesel) to the oil filter (fuel filter) to be installed on the diesel engine.


3. Leave the oiled filter still for half a minute, then refuel the filter.


4. Repeat step 3 multiple times until you are sure that the air in the filter is completely discharged and the filter is filled with oil or fuel.


5. Apply a thin film of diesel lubricated oil onto the end of the filter seal ring, then install the filter onto the filter sear and rotate the filter until its sealing ring is in contact with the filter seat.


6. Then rotate the full flow oil filter, the side oil filter and the fuel filter by 3 / 4 / 1 and 1 / 2 / 3 / 4 respectively (the installation torque of the oil filter with rectangular and conical sealing rings is 45~50ft-1bs and 15ft-1 A (61C 68 and 20.5N.m), respectively), be careful not to tighten too tightly.


Note that it is absolutely not allowed to install the unrefueled filter directly on the filter seat, otherwise it will cause a series of serious problems, such as burning tile of diesel engine, crankshaft locking, dry friction and wear of parts, damage and so on.


In the fuel filter, because the specific gravity of oil is lighter than water, water deposits in the lower part of the filter and oil is above water. When water is released, the plastic cock at the bottom of the filter is rotated first, the filter releases the pressure first, then the water flows out first, and then the oil flows out. When the water in the filter is estimated to have been basically discharged, the screw plug or the tight plastic cock is installed immediately.


Fault diagnosis and Analysis of Diesel Generator fuel system


Because the diesel fuel system of diesel generator set is working under high temperature and high pressure for a long time, there will inevitably be various problems and faults. Based on the practical troubleshooting experience for many years, our engineer summarizes the common faults and causes of diesel generator fuel system as follows.


1. Low pressure has leakage (using drip method, if the oil quantity meets the requirements, it is low pressure gas leakage, the following parts should be inspected.)


(1) Oil pump intake pipe

(2) Firewood filter (diesel engine power is not enough, should be checked first, cleaning filter element).

(3) Firewood filter pipe

(4) Hand pump (where most problems occur)

(5) Tank vent (to exhaust air to see if it is blocked)

(6) Fuel tank (oil tank suction pipe is welded to the box, its weld crack or pinhole will make air leak into the fuel system, which is often ignored).



2. Governor malfunction (the manufacturer has adjusted it, no one can move)


3. Smoke limiter failure (it is a component that affects the performance of a diesel engine, the manufacturer has adjusted it, no one can move, otherwise it will affect the power and exhaust smoke of diesel oil generator set).


The smoke limiter on the smoke limiter uses the air pressure in the intake pipe to adjust the air-fuel ratio to achieve the purpose of controlling smoke. Damage to the smoke limiter will result in insufficient power and increased exhaust smoke. If the intake pipe to the smoke limiter air nozzle leakage or blockage will also cause a decrease in power and smoke exhaust. If the vacuum tube on the smoke limiter breaks, the power of the diesel engine will decrease.


4. Diesel engine low idling adjustment screw can be adjusted (if the idle speed is too low, it will cause the enigne to swim at idle speed).


Note: high idle adjustment screw should not be moved at will, otherwise it will cause engine problem.


5. To determine which cylinder does not work, use the broken cylinder method to check. After determining which cylinder, remove the faulty injector for debugging, and check that the injector is overloaded with sealed copper gasket. At the same time, check the injector for failure, can be connected to the engine outside the test.


6. Return oil (check the fuel return of the diesel engine in genset at rated speed to determine if there is a problem with the fuel flow).




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