u/notjeshorisitmaybe

I just had the cp3 conversion done on my 2016 Duramax and now when I park on an incline it loses prime. I took it back to the shop and they can’t find a problem but want to charge me $1600 to put a fade on it and hope that fixes it. I know the filter housing is a common issue on these but my hold up is it always started fine before I had them do the conversion and now it’s everytime I park it on a hill facing up it does it. They pressurized the tank and claim they could find no leaks or anything so they claim no fault. I just don’t really want to throw $1600 on it a week after spending $5000 on it for a problem that wasn’t previously there