Trouble starting Peterbilt

Likely a fuel filter/water seperator O ring damaged.

Can you post a pic of the filter/housing?

 

Looks normal, but I would be pulling that bowl and checking that O ring, and make sure the nut is tight.

If it 100% didn't start this until serviced, always start with the last things touched.

Did you pick up the fuel filters for them?

To me, a greasy Carquest fuel filter doesn't give me confidence these were professionals.

 

Definitely would double check the o-ring on the filter. I've been burnt by that in the past.

 

If it happened after oil/filter change... maybe air in the system... if u have a 2350 isx there is 2 compucheck valves right on the primary filter . You can prime the air from the system using these... don't remember what fitting goes on there. I had a truck stop mechanic get so much air in the system after a fuel filter change it was missing so bad it wouldn't even idle... I lugged it to peterbilt across the street and they pulled an incredible amount of air out of the system and it was good as new... they had a special fitting to connect though..

This picture is of an x15 but it's the same concept. Pull that cover off and there's a nipple to connect to and you can pull prime thru there. If u can find the correct fitting all u would need to do is connect it to the compucheck valve and cycle the key a half dozen times , have a bucket to catch the fuel

 

I’m not too familiar with isx I run a celect plus. If these have a check valve remove and clean. I had the same problem. Sometimes would stay running but most of the time I had to keep foot on pedal to start. Always had to start at least twice before it keeped running. Could also a vacuum leak on air to air or leak in your supply fuel line that you can’t see. Check valve sounds more like it though. Hope this helped. Good luck driver