Hey new to forum great site by the way been a lurker for years,Anyways have a 2003 2500hd 6.0l with hard starting issue.I have replaced the fuel pump,filter and fuel pressure regulator with oem gm parts and still have hard start issue.It will start cold just like when it did new,but when warmed up wil turn over 4 or 5 seconds before starting. Im totally lost at what it might be any insight would be greatly appreciated.thanks Ty

 

Do you have check engine light? Sounds like egr or some other related emission issue.

 

no cel had it tested because didnt trust the cluster and no codes come up except a while back an o2 sensor code came up but hasnt been back .

 

trying to relate this to a "heat" issue. O2 sensor sets in the exhaust, maybe it, and no code. Intermittent sensor. those aren't too exspensive.

 

i dont really know but i cant see the o2 sensor being the problem though maybe?

 

Just picking at the problem, don't know, but I will add just because that part was replaced or "new" dosen't mean it it works (unfortunatley) Unfortunatley the ECM, PCM and how many other mcms. The ecm has to see multiply errors before flagging a code, so, if the 02 is doing it intermiten, and clearing, it might not throw a code.

 

i took it to a shop a while back and the guy told me it could be the thermostat in the radiator?causing hard starts but it always seems to read right on the gauge though.

 

What was the cure for this issue? I have the same issue with new fuel pump and regulator already installed.

 

Did you figure it out i got same problem

 

I have a similar issue. It starts fine cold, but when its warm it doesn't want to start. It says my RR door is open when its not, also says service air bag, and sometimes (not very often) I will be driving down the road and my anti theft system will shut down my radio and cluster, sometimes it doesn't restart then I have to stop the truck shut it off and open my DD only then it will restart.