For twenty years my First Generation Dodge Cummins started with just a bump of the key. About a year ago it began requiring brief cranking, then to more cranking. Occasionally it needed bleeding of couple injectors. Recently it refused to start with bleeding and extensive cranking, then did start with a pull.

The fuel lift pump has been replaced twice recently. Fuel filter and its water drain replaced.

What's going on?

 

Welcome to DTR.

My first guess is you have air getting in the system anywhere from the injection pump to the fuel pick up on the suction side.
Think loose / broken clamp, dry rotted hose, cracked fuel nipple, leaky fuel filter housing gasket, loose banjo bolt...ETC.
This allows the fuel to run back to the tank when parked. I have seen where parking the rig nose downhill rather than nose up hill will keep the fuel from draining back to the tank during periods on the truck not running.

 

Thanks Oliver. Would it help to know that the refusal to start can occur immediately after being driven and shut off? Drive, shut down, crank / crank / crank (and maybe not start).

 

Yes that bit of info is key.
I assumed you where taking about after parking say over night or while at work for hours.

I would still say you likely have a bad connection somewhere that is allowing air to be sucked in the fuel line from the pressure the lift pump makes.

 

Will check what I can of the connections and hoses

 

I have used the pressurize the fuel tank and look for wet spots at connections trick before with good results. I say this as the leak will not show a wet spot under normal driving conditions as it will be under vacuum rather than pressure.

If you do pressurize the tank only use a PSI or two for safety.

 

That sounds like a plan. Thanks.

 

Posting the year of the vehicle in question will help, also. The early trucks used rubber hoses and steel lines, while the later ones had plastic lines and o-ring connections. When you pressurize the system, be sure to look closely around the fuel heater and fuel filter.

 

Thanks. It is 1992. Lines appear to be steel