I've had my rig since it was new and I never REMEMBER this happening before.

Sometimes when I turn the key the lift pump won't come on. If I wait 5 - 10 seconds it comes on fine. I also notice sometimes the wait light comes on on the dash, in the 18 years I've owned it I never remember that coming on no matter how cold it was. I'm not talking sub zero weather just normal 50 degree start ups. It will even delay after some trips and the engine is warm.
The pump runs fine once it starts, it puts out good pressure, doesn't shut down once it starts and at times even on cold (low 30s) mornings it will spin up as soon as I turn the key.
Is there some delay circuit that just started working for me or am I looking at a brain transplant soon?

 

Not normal at all.

Lift pump runs as follows:

- 2 seconds when key turned on before starting
- 25 seconds after failed start or bumping the starter
- Runs at 1/2 power while cranking
- Runs continuously at full power when the engine is running

Wait to Start light operates as follows as soon as the ignition is turned to ON:

- 2 seconds at 60º and above, grid heaters not used
- 10 seconds between 31º and 59º, grid heaters also turned on for 10 seconds
- 30 seconds at 30º and below, grid heaters also turned on for 30 seconds
*note - at 59º and below the grid heaters will cycle on and off for 5 minutes after starting to assist in engine warm up.

If the lift pump or WTS light don't work like they should as noted above, then the ECM is likely having issues. The ECM powers the lift pump directly, and it controls the grid heater relay. The WTS light is the only light on the dash that the PCM does not control, it is wired to the ECM only and is usually the first indication that the ECM is having issues.

 

That's the way I remember the lift pump working.

The wait to start light has NEVER worked like that. I didn't even know I had one until this year. My grid heaters have always worked and still do based on watching the lights and amp gauge in the morning.
I need to put my reader on and see if I have any codes I guess. I know my tranny is crapping out. Note to all, check out the shop before getting work done. I got coerced into using a local transmission chain that begins with C because it was within towing range. and it's been two years with constant problems and now it stays locked after highway speeds, won't engage right when cold and sometimes won't go from 2nd to 3rd unless I let of the pedal.

Hopefully it is just giving my rig a headache and after the tranny is fixed the lift pump will work right again.

 

If you can get the sensor values read out by your code reader (or any other way like torque for android) take a good look at what the ECM sees for coolant temperature and intake air temperature.
If the ECM sees something wrong but still plausible you will have a behavior as described.
About your transmission- take a look at the wiring, maybe they pinched or damaged some wires, this can drive you mad, because a lot of the 5V sensor systems are interconnected.
(Had a customer where the water temp sensor wire had rubbed through, tranny started to shift erratically when it got ground)

HTH

 

Give Tim a call at TRE Diesel, he's the best in the area at these Dodge diesels.