i have a 99 cummins and when it sits for a day the batteries are grave yard dead. also when the batteries are good it seems to not get fuel (it just turns over) but if i hook a battery carger up it will fire right up. just replaced fuel pump and on my fuel presure gauge i am reading normal (15 psi) until i go to fire then it drops to 1 psi i am thinking injection pump. anybody else have any ideas?

Im thinking low side restriction

but the batterys are first issue, need solid CCA before anything else can be diagnosed
are your batterys in good state of health and have a parasitic draw or are they just bad?
one bad battery can take out the other so test them both carbon pile test or a load tester w/e is available to you
min cranking psi should be 7psi , clean filter and lines that are not kinked or restricted

does the engine run? after boosted?

with what you have said so far this sounds like a low side supply issue

good luck
scott

The lift pump does not run while cranking so you will have low psi while starting. As long as psi is normal right after it starts your good.

ugg , bryce is 100% correct, I meant running psi not cranking psi, lift pump shuts down during starter engage sry for the misinformation

but im still not convinced of a pump issue yet