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I have a fuel pressure gauge on my dash. I got it, and an F/A meter, for the dash some years ago when I was going thru engine management hell. Lately I’ve noticed that my fuel pressure is around 35psi at idle and a little more at WOT. I didn’t really remember what fuel pressure was supposed to be, but 35psi nagged at me as a bit low. I checked Bentley tonight and apparently I’m 5psi low.
I’d never have known this if I didn’t have a fuel pressure gauge on my dash. Something to think about.
Should be 38 idle 43 WOT. Get a new FPR and check the vac line to the intake. Check voltage at the pump. Check part numbers of fuel injectors (seriously).
Bentley says the FP should be 40.6 to 46.4psi, with engine running. On the low end of that at idle and at the high end of it at WOT. My fp is 36-39psi depending on engine load, so I’m down at least 4psi. It’s a race car, I don’t want to be down 10% in FP, especially when E90 gas requires the injectors to spray 10%(?) more fuel.
My point tho wasn’t to complain about my problems. Everyone’s car has it’s own problems. My point was to encourage folks to have a fuel pressure gauge on their dash. Even better if it’s wired to a data logger.
I’m confused if this thread is about having a fuel pressure gauge or Scott’s low fuel pressure, but feel inclined to comment.
Our cars run a 3 Bar (43.5 PSI) regulator and would expect exactly that pressure under load. In a proper running engine, one without vacuum leaks, pressure should be in the high 30s at idle or when the engine is at high vacuum conditions.
Scott, check to make sure you don’t have an eta FPR which is factory set at 2.5 Bar (36.2psi). Otherwise, I’m suspect of your gauges and think you should install several more gauges to check the accuracy of the current gauges! 
Re. 2.5bar FPR. That’s an interesting idea, I better check. I bought my FPR, it’s not a used take-off, but it’s certainly possible that there was confusion and I’ve been running an eta fpr for the last 3yrs.
If that proves to be the case, I’ll be laughing about it for months.
I pulled off the FPR last night and it’s clearly labeled as the correct one. The part # was right and it said 3.0bar. If I get a chance to work on it tonight I’ll grab a used FPR and see what I get. Who knows, maybe my (not cheap) gauge is reading the wrong FP.
I couldn’t install a spare FPR last night because most of my spares are up in the attic, and getting up there would have woken the kids. I’d already accepted risk by running the car a few times around midnight with the garage door open.
Mystery solved. I pulled a sad looking take-off FPR out of the attic, confirmed it was 3.0bar, installed it and instantly gained 7psi. FP is now ~43psi at idle.