My first post. I searched and couldnt find anything on this issue. I already changed the fuel pump, but still has the same problem. When I start the truck my fuel pressure is it about 400 to 450 kPa. Once it warms up a little bit I noticed that it drops to 300 kPa. Mind you it does this regular as if it is set by some device to do so. There is a noticeable difference in my idol when it drops to 300 it's it's rough but then when it jumps back to 450 it's nice and smooth. I have a 220 220 581 581 114+4 sleeper cam. My question is what would cause this and how do I fix it.
Thanks for your help in advance
Johnny

 

What kind of truck?

Newer trucks have fuel pump control modules that will drop the fuel pressure when 58psi is not required.

 

Well, that makes sense. It just seems like I should have more power. I watch my pressure and on wot I'm not seeing an increase in pressure. Should I be looking at something else? I have the aforementioned cam in a Gen4 5.3 with Pacesetter long tube headers, Flowmasters, polished 243 heads, CAI, and MSD wires. It's a 07 crew cab. I have a G80 w/ 3:73 gear. I know this is a dumb question, but any idea what I should be at 0-60. Im just trying to get a ballpark. I'm new to the whole fast truck side of the house.