Sudden loss in fuel economy after service

[The j man]

Hi guys,
2008 nissan yd25 diesel
I did a service new oil, air filter etc
Fuel filter is 10k old
Did and injector purge a few months ago
And I had the diesel return line that comes out the side of the cylinder head leaking oil so I tightened the nut on it which is not the right one for it and the pipe that comes out of the cylinder head twisted with the bolt, when I twisted it back it crimped right where it comes out of the head after the thread, so I cut it off and connected the return line directly to it and tightened the hose down with a clamp, doesn’t leak seemed okay, then after I drove the car im getting 24l per 100km sometimes more on regular driving, I reset the gauge and same thing.
many ideas

 

[tweak'e]

not 100% sure on those but i think the return line goes back to the suction side of the injection pump.
so odds are its sucking air in which is causing loss of performance.
really need to pull the rocker cover off and fix that return line and VACUUM TEST IT.

 

[Nig]

Hi guys,
2008 nissan yd25 diesel
I did a service new oil, air filter etc
Fuel filter is 10k old
Did and injector purge a few months ago
And I had the diesel return line that comes out the side of the cylinder head leaking oil so I tightened the nut on it which is not the right one for it and the pipe that comes out of the cylinder head twisted with the bolt, when I twisted it back it crimped right where it comes out of the head after the thread, so I cut it off and connected the return line directly to it and tightened the hose down with a clamp, doesn’t leak seemed okay, then after I drove the car im getting 24l per 100km sometimes more on regular driving, I reset the gauge and same thing.
many ideas

Did you do a pump reset

 

[The j man]

I bought a new return line put it in did the reset and I’m still getting 25lph I did a fuel purge and still

 

[Tms40]

Is that your dash gauge giving you the mileage or actually measured?