Rail Pressure question

[retirednak]

I have a question & hopefully the answer isn't expensive. I noticed my fuel rail pressure gauge fluctuating while driving down the road at a steady RPM. I have close to 135K on my entire fuel system, other than Airdog LP. Truck runs fine, doesn't smoke and each oil sample sent to the lab looks good. The rail pressure fluctuation seems less if Smarty is turned down or off. Usually run it on 2 added timing, raise rail pressure setting is stock. Since my truck is an early '03, it's the 250 HP model and every little bit helps fuel mileage. My fuel pressure gauge took a dump so..I've replaced both AD filters and now that winter is here, need to get my truck back on the road. Watching the RP gauge moving at a steady RPM makes me nervous.
What say you?

 

[Killer223]

it fluctuates from load. mine will bounce from 7K-13K with cruze set at 70. even idle mine moves...
however if it swings way hi and way low. and idle changes with it's swing you might be looking at a new FPR. i['m told they are easy to change... i have no other information.

 

[cerberusiam]

Some fluctuation is normal, the sampling rate of the gauge will cause that. Even looking at it with a scanner it won't be perfectly steady.

Without knowing what you are running for constant pressures and how much the fluctuation is no way to say one way or another. Need more exact info.

 

[retirednak]

Since some fluctuation is normal, I'll quit worrying about it. Mine has never dropped below 8K & always seems to be around 12-13K running at steady hwy speeds. The gauges can save a guy & drive & worry someone up a wall!
Thank you for the info.