Cummins N14 start problem

Have you tried a different brand of fuel filter? My truck starts very hard with certain brands. I guess it's because of that rubber gasket on top of the filter not sealing well enough

 

What type of fuel filter, Davco or spin on?
You should have a check valve to prevent bleed back. This valve is mounted in the fuel output of the cooling plate mounted behind the ECM.

 

You don't

 

That would be my first place to start.

 

Some not all Davcos have a check valve. Some not all N14 cooler plates have a check valve that looks like a fitting but comes apart. There is a small filter in top of pump under round plug that can hold junk.

I would consider putting supply line into clean bucket of fuel and test. Isolate engine from truck.

 

Some filters that cross reference to the Fs1000 do not have the ainti siphon stand pipe. Some do not.

 

I always used FS 1000 on that engine - no alternatives. I think Fleetgaurd is the Cummins brand.

 

That check-valve was designed to slow down drain-back during a filter change and nothing else. You can take a brand new check-valve and blow backwards through it. I can almost guarantee you there is wear inside the pump allowing the drain-back issue you describe, personally seen it many times.