Cummins HPI-TP fuel system introduction
Maintenance points of HPI-TP injector
First: Metered fuel inlet check valve and timing fuel inlet check valve
During the oil intake process, these two valves (Figure 2) will be opened under the action of the pressure pulse to fill the metering oil chamber and the timing oil chamber respectively, and these two valves need to be closed in time when the ejector rod descends. In order to generate high pressure in the internal oil cavity of the fuel injector, if the two one-way valves are severely worn, the sealing will be weak, which will lead to errors in timing and fuel metering, and cause the fuel injector to fail.
Second: Upper plunger
Third: Timing plunger
Fourth: Overflow pressure maintaining valve
Fifth: Lower plunger
The side of the lower plunger plays a role of sealing the high pressure oil in the metering chamber, and at the same time there is an oil drain channel in the lower plunger. If the side wall of the lower plunger (position 4 in Figure 3) is worn, or the side wall of the corresponding injector is worn, this will cause the fuel high pressure inside the metering chamber to leak, which will lead to insufficient injection pressure and delay the injection time; at the same time; , The injected oil volume becomes smaller.
Finally, let’s make a summary of HPI injector repair and inspection together:
1: Check whether the bottom of the upper plunger, the side wall of the timing plunger, the side wall of the lower plunger (with overflow oil passage) and the inner wall of the corresponding injector are severely worn. If there is, it will seriously affect the performance of the injector. Need to be repaired and replaced.
2: Check the timing check valve and check whether the metering check valve seat surface is good.
3: Check whether the sealing surface of the fuel nozzle is in good condition. If the bottom of the lower plunger has a large black area, it means that the sealing is not good and the exhaust gas has been able to flush into the fuel injector. Need to remove the blackened carbon deposits.
I hope this article can help repair stations that currently have HPI service business. We will share it on the official website and other platform websites in the future.