Since having the FASS pump installed, sometimes my truck won't start. Today I had to roll it over for 6 -7 seconds three times before it finally started. It doesn't do it all the time but it has only done it since the FASS pump install. Any ideas what is causing this?

possibly and air leak where the FASS ties into the fule system?? Is there any common with the times it does it? ex) truck sits overnight?

seems to do it more often when fuel level is below a quarter tank. But it still does it after tank is topped off.

I'm hesitant writing this because I know little about the Dmax injection system. On Cummins, the ignition switch is wired to give the lift pump an initial startup to develop pressure, then shuts off. The pumping lasts a couple of seconds. Pressure then slowly falls for engine startup. Problems people were having with aftermarket lift pumps (FASS being one) is they developed too much pressure for the injection pump, which led to hard starting. I don't think Dmaxs have lift pumps but you might want to try turning the ignition on and waiting a few seconds before hitting the starter. I had a FASS setup for years and it was a big improvement over the stock pump.

seems to do it more often when fuel level is below a quarter tank. But it still does it after tank is topped off.

Do you have a 150gph or 95gph FASS? This is a known issue with the 150gph..

Sounds like some where u are getting air in your line Check your hoses

95 gph since I don't have big tune to keep up with. It has started and ran fine the last couple of days.