Fuel pump

I had an International pickup I did this on, I just had a switch on the dash to prime the mechanical pump with the electric one. Whether or not this is a good idea, I don't know. They're both Internationals though so it's bound to work. Even if it was a 392 gas burner.

I will say that you can have air leak in a hole that's too big for fuel to leak out. I mean, the air has to be coming from somewhere.

 

Yes, you have air coming in somewhere.

 

I don't know about the N-14, but my ISX has what they call a fuel lift pump, that is NOT the main fuel pump. It went bad, and I could tell because I had to do more cranking to get the engine to start, and it was dripping a little.

 

Very lightly pressurize your fuel tanks look for fuel leaks

 

I know it's a totally different truck, motor and fueling system BUT, on my Mack I had the same problem...cranking the engine forever before it fired, sometimes it would spit and sputter then die.

There's a small return line running from the head down to the big fuel return line. It had a pin hole in it, wasn't dripping/leaking...just damp around the spot. I replaced that small line, primed it back up and it fires now with just a flick of the key.

Moral of the story...even though there may not be a distinct leak, you're losing prime/getting air in the system somewhere.

 

n-14 has only one pump, have you looked at the check valves around the ecm cooling plate they could have a piece of trash keeping one of them open

 

Are you sure the check valve on the Davco unit is sealing good? This would be the big brass fitting screwed into the base of the filter that the line from the tank goes to. I had a piece of trash in mine that caused troubles.