Cummins N14 Stumbles on light acceleration

Many possibilities.
The Yellow Check Engine Light. What codes are you getting. Do you know how to get the codes from your truck.
My truck 98 freightliner with N14. It will sometimes have hesitation. My connection to the boost pressure sensor in subject to moisture. This is on the end of intake manifold facing the firewall . I have replaced the sensor and same problem. I take the connection apart, clean it, put back together. This will work for a week or couple months.
Also could be an actual loss of boost air from turbo.
Read your engine codes that will give you a good idea where to start looking.
Good luck.

 

Can you post a pic of the valve and where exactly is located, probably should check mine too

 

The filter on the pump. I was told you should never have to change it. OF course I did as soon as the mechanic said I shouldn't have too.

 

The

The valve is located on plate that is mounted behind your ECM. IF you follow the input fuel line from your fuel Filter back to the ECM. That junction there where the line connects to the Aluminum plate is where the check valve is. There really isn't that much to the check valve. Just a ball with a spring behind it. It is suppose to prevent your system from draining out every time you shut down.
One nice thing about the N14, it is self priming.

 

The check valve is at the top left corner at the back of ECM.
If you look above and behind the black hose with the yellow stripe. That black hose is the fuel feed to the filter. It curls above the braided line that is the compressed air line. Just above the rubber hose on the braided line you can see the cable tie in the back. That is where the fuel line and the inline check valve is located. The check valve just looks like a part of the connection on the cooling plate.
Good luck.

 

On the freight

On the freightliner there is. Not sure about your truck.
Under the starter key. I have 2 toggle switches. One is to raise idle. The other is to read the codes. Without starting truck turn the key on. Now on your dash the red engine light will come on and flash once and stay on, and the yellow light will flash three separate numbers. Say `121
It will flash once, pause, flash twice, pause, flash once, pause. Then repeat. Then you look up the code here
http://www.diesel-service-parts.com/cummins-codes.html
Then get your manual here:
https://www.manualslib.com/manual/809857/Cummins-N14.html
Then register here, these guys are helpful once in a while:
https://quickserve.cummins.com/info/index.html

The best help I get is on TTR. Most guys here have not only read about it, but have actually done it.
Good luck.