DD15 Hard Starting....

Yup your davco is letting air in somewhere.
There is also a check valve on the davco that prevents drain back to tanks.

Take the davco apart check that check valve and also make sure the bowl is not cracked and all O-rings are in good shape .

Also make sure the cap on very top of glass bowl is tight

 

It might not even be your check valve but it is something you should check .

Take the fuel line off going into the davco,you should get no fuel escaping .

There's a couple different models of the davco, go to your dealer and order a new check valve if yours is bleeding back

Did you check the cap on top of glass

 

No fuel will not leak
The valve just prevents fuel back feeding back to tanks so you don't loose your prime.

 

your davco should be filling up as you drive.it can take anywhere from a few thousand miles to 25,000 miles before it is at the top & needs changing. the back check is where the fuel inlet goes into the davco. on my unit it is a huge nut inside there is a piece of plastic holding a black ball & a spring. a part may be broke, or many times a piece of trash can get caught in that area & cause fuel to drain back into tanks. make sure other collar & O rings are air tight.

 

it also may be the back check in your engine. or you may be sucking air somewhere.