I have an 05 3500 5.9 Cummins with 160k miles. It will not start cold and by cold I mean if shut off for greater than 8 hours. I tried starting it in the afternoon outside temp was 90f. Turned over no drag just wouldn't start. I gave a little shot of starter fluid and it started ran it for an hour shut it down for 15 min re started but after turning over 7 or 8 times. Took it to the shop replaced the in-tank fuel pump, filter and updated ECM. Shop called and said still had problem needed new batteries, then called back and said batteries ok just needed to take the fuse panel lose and clean. They gave it back and no start the next morning. Batteries showed 13.5 volts, I can hear the heater, another shot of starting fluid and she starts. Any Ideas really need some help!!