My truck ran reall funny this morning when I started it. I installed the bigger tank yesterday.

What would the sysmptoms of a small air leak be when starting?

It was surging real bad (150rpm) from a dead cold start.

Did it get better once it ran awhile?

Yes

Might be air working its way throught the system but probably to soon to tell.
When I put on a new filter it takes a couple days for all the air to work its way through the Mega.
I'd give it bit before I'd worry to much about it.

Blake

When I had air before lift pump install I'd get a hard start and die deal.
The lope I have now is not air related.

Blake

So my fuel pressure reg or fuel pressure return sensor is going out real quick huh?

With your luck PC (or lack of) you probably need a new engine.

I'm just telling you what my observations were regarding air in the fuel system.

In my case the lope or surge is not air related.

Blake

i'd probably guess that it is because you just installed the tank. you of course introduced some air. if you changed any filters at the same time i'd make sure they tight and seated properly, but usually the air will work itself out if there isn't enough to stop the engine..

Diesel power you were correct.

I just went out and started her and she ran without surging.

I still have the 25-50rpm lopey idle when warm.

Ill wait for it to get worse and have them fix it after my vacation.