I have a 99 RAM 2500 diesel 4X4 with a manual transmission. This truck has just over 250K.
The injector pump was replaced about 225K. The lift pump was originally replaced at about 120K and I just recently replaced it again in hopes to fix this problem. Also the fuel filter is new and made no difference or change. The truck starts and runs fine and gets good mileage normally, but......... After its been sitting 12 to 24 hours it has a starting problem. The truck will start immediately (if on a flat surface or downhill with the front of the truck lower than the back) run about 10 to 15 seconds then die from some obvious fuel starvation. It will take a good minute or 2 of cranking before it will start after that. All the fittings, fuel and injector lines and banjo bolts appear tight and no visual or obvious signs of leakage. If the truck is parked on my uphill driveway with the front of the truck higher than the rear, it just won't start at all until after the minute or 2 of cranking. Once started the truck works great all day.
I think its safe to say there is air working it's way in some way somewhere, but I don't know how to determine source. No obvious visible leaks. Any suggestions guy's?

 

my truck did the same thing and i found a leaking injector. it never wouldnt start just had to crack for awial. iv also heard that the check valve in the return line can stick. if you pull the banjo bolt on the injector pump there is a ball in it push it in next time it wont start and try that. there are also small orings on the end of the injector line right were they go in the moter. check those too. hope that might help

 

It sounds like you still have a "stock" system - with banjo bolts.

If you are just repairing the system and keeping it original - it will fail again. It will adversely affect your Injector pump (IP).

If you can't afford a good (but expensive) lift pump, then relocate the Lift Pump (LP) to the rail - putting it lower and closer to the fuel tank - this will help the LP last longer and work better. Get the kit(s) to remove banjo bolts - this will improve the flow and help the pressure be higher at the IP. Get a fuel pressure gauge and warning light. You can do these basics for under $200.

 

I would definitely start looking at aftermarket liftpumps if you are still running a stock one. When my stock one went out, it would start fine one time and then it wouldn't want to start the next. Even if your stock one is still good, replace it with an aftermarket. Even when they are working they usually don't make enough pressure to keep your injection pump happy