Pressure should be steady when motor rpm is steady. Any fluctuation is either gauge or spring. When is last time you changed filters?

 

Needs filters. Last change 36k ago. Recently did the Blue Spring upgrade. I spoke will ISSPRO yesterday and they weren't that surprised that it fluctuates as it reads 1000x per second. However, you and most others that run them seem to feel it should be steady. One thing that ISSPRO suggested was to turn to key on and engine off position and see if it is stable. It is, and they say it isn't the gauge then, and that it is just reporting what is actually happening in the bowl. Thinking I'll do the filters and then reassess.

 

damn, filters are due every 10k or every 2nd oil change

change those puppies out.


the gauges may read 1000 times per second. cool. but it should see the same value consistently when at level RPM and no speed/rpm variances.

 

Changed them out, but no change. Starting to believe all is well since the gauge readings, while not rock steady, always seems appropriate to the situation and always stay between 60 and 64. Unless you have other thoughts, I'm just going to start being happy. Full disclosure: I wasn't happy on the first day when it WAS rock steady, as I believed it was yet another dummy gauge like the ones on the dash. Seems you can't make me happy.

 

I have had the same problem for a couple of years. I have researched this forum and others and I haven't found a final solution. I even hooked up a mechanical gauge and saw the same fluctuation. I have an electric sender and a DashDaq for monitoring and my fuel pressure still fluctuates. I came to the same conclusion as you. I electronically filtered the signal with the DashDaq so the fluctuation so it wouldn't bug me. I did see one post where one fellow changed his fuel pump and the problem went away.

 

I also suspect the fuel pump and, like you, will continue to try to figure out why this is happening. Obviously, our trucks (mine and yours) don't have a steady fuel pressure. While a steady pressure would seem to be ideal, I'm not sure it really matters in the long run. Is there a way to test the fuel pump OTHER than to measure fuel pressure?

 

Subscribing.

I also have the fluctuation and like wgcdc and I've been averaging the reading over 1.5 sec on a dashdaq to keep it steady. Mine was also verified using a mechanical gauge.

I'm still under warranty, but do not see the dealer doing anything unless it throws some sort of code. Are there codes for the fuel pump?

 

I have a Attitude Monitor, a ScanGauge II, and now the ISSPRO fuel pressure monitor. I'm running out of monitor space. At $500+ for a DashDaq, I think I'll just watch my needle wiggle, particularly since I still know that, even with a DashDaq, it's really still wiggling. I just can't see it.

 

To answer your question, I don't know if the fuel pump specially would throw a code or not. I would let me dealer know since you never know what they will say. If they replace it and it fixes the problem, let us know. If I knew that pump replacement would fix mine, I'd sure replace it.

 

I added a mechanical FP gauge and found that the FP is steady at 59-60psi, while the electric is jumping.

 

Well that's 2 unsteady on a mechanical gauge and 1 steady. I don't know about mine since I don't have a mechanical gauge. I'm working on a homemade snubber as described in the "other" thread. I'm now waiting on the Swagelok people to call me back with a quote.