[Mudman]

I have a 2007 classic that is bone stock except the exhaust that trows the code when i pull a trailer. Here is what i have done.New ac delco fuel filer, Cked the fuel tank for trash,used a vacuum gauge to ck fuel line restriction and it's no more than my o4 took it to the dealer they ran checks on it and said to replace the high pressure valve so i did. It still does it!!! HELP.

 

[TPDiesel]

What you need to do is find some one with EFI live or a Tech 2 and have them plug it in. Then watch the actual rail pressure and desired rail pressure while your towing.

 

[JimPick]

I have a 2007 classic that is bone stock except the exhaust that trows the code when i pull a trailer. Here is what i have done.New ac delco fuel filer, Cked the fuel tank for trash,used a vacuum gauge to ck fuel line restriction and it's no more than my o4 took it to the dealer they ran checks on it and said to replace the high pressure valve so i did. It still does it!!! HELP.

The problem is likely the fuel lines. Rubber fuel lines may have lost rigidity with age and may be collapsing due to excess heat from exhaust gas recycling chamber when towing.