I have a 04.5 2500hd duramax that I just replaced an Injection Pump from Industrial Diesel that has 45% more volume and added a FASS Lift Pump. I did this because my original CP3 pump was going out and kept giving me P1083 codes. I got the truck running yesterday, fixed all the water leaks (gotta love the o rings) and now I keep coming up with a P0089 DTC for high fuel rail pressure. I called Industrial Diesel and they told me to cut one coil off the pressure spring on the FASS lift pump, I did that and I still have the P0089 code, every time I erase the code it comes right back.

This truck is purely stock, it has just the modified CP3 pump and lift pump no tuners or anything like that, I have 4" straight pipe exhaust from turbo back.

Can anyone guide me in the right direction on how to fix this code?

 

I really need some help on this, I am pulling my hair out trying to figure this out, I dont think its the Fuel Pressure Regulator because this pump just came from Industrial Injection can any one help me out on this at all?

 

i would hook it up to some kinda scanner with live data...what ever you can get ahold of...tech 2...efi live...something and compair the desired rail to the actual rail pressures

 

I have a Snap On Modis, the desired is supposed to be around 30 MPa at idle and I am around 160 to 180 MPa. The desired when wide open and off idle is perfectly matched from 1300 rpm and higher. I cut the return spring down 1 whole coil on the FASS as I called Industrial and that made no differance at all. So now I have a low pressure FASS lift pump and I still have the same codes come back with in 45 seconds of clearing it.

My dad on the other hand is asking me if the computer is seeing the extra rail pressure from the modified CP3 and kicking the check engine light and putting the computer into limp in mode. He also said that it sounds more like a cummins motor now then a Duramax.

Now when I first took on this upgrade it was out of opportunity because I was getting the truck into limp in mode behind the P1093 code. I am wondering if this was actually caused by a bad pump or if it was actually a fuel pressure regulator or the FRP sensor. After getting the new CP3 from industrial that for the amount of money I spent with them I would have at least got a NEW fuel pressure regulator but I wont have the answer to that question until tomorrow morning. I'm not replacing any other parts until I talk to industrial and find out if this is a common thing to have happen when using the modified CP3 pumps, I only got the 45% pump and not the 85%, I don't plan to go wild and if I do, I can just add a dual CP3.