Question about my truck and hard cranking issue

I'd still check your batteries, bad batteries can do strange things on these newer vehicles. The reason it fires right up with ether is because is causes an instant spark without the engine having to turn over much.

 

if it has a hand primer, try priming it and see if the primer gets firm, if it doesn't or if the primer loses prime shortly after you most likely have a leak. even a slight one can cause a headache. also check your primer as they do occasionally go bad and create a place for air to get in the fuel system

 

If it cranks slow I would say batteries. If it turns fast but just won't fire I would look for fuel leaks. Could even be an injector leaking down.

 

Loosen the check valve your mechanic replaced and have him re-torque to the proper spec. Torque it to 18 ft. lb. If he used the updated check valve it is a "spool" type rather than a ball and spring. Overtorquing the spool type will cause it to hang. Here's what happens, you install and tighten too tight,you crank the truck and it builds excessive fuel pressure until it's enough to overcome the resistance of the improperly torqued check valve which then opens. You cut the truck off and your spool in the valve still remains open since it's "pinched". It will build pressure still but when engine is off the fuel slowly drains back to the tank. That's my suggestion. Also check the inside of the base for a sharp burr that could possible damage the back-up ring during installation.

 

Ok, is this unit slow to crank, or cranks over nicely, but hard to fire?

 

check how much fuel you have, i seen trucks that dont start. only cos too low fuel

 

It is losing it's prime some where. you say you done away with the check valve? you took it out? I had the same prob years ago with my det. it turned out to be the back check at the back of the head.

 

I'm leaning towards the check valve..........pull it out to see if the o-ring isn't cut. Then as CAT FLASH suggested don't over tighten it. When you install these valves it's easy to cut the o-ring if you don't lubricate it properly with fuel first. I found out long ago if you use oil they have a tendency to get cut the o-ring. This valve is the most common reason for hard start issues after the truck has been sitting for a few days..........they stick open allowing the fuel to drain from the cylinder head to the tanks. If the back-up o-ring is cut, then it does the same thing along with low fuel pressure after you get it running.

Also as Rig Wrench says, the primer pump located on the fuel filter base can go bad and allow air into the fuel system

 

Ran mine out of fuel once, had the same problum after that. Had to replace the supply line from tank to pump, colapsed inside, looked new outside. solved the problem !