I am always ranting about rail mounted fuel pressure gauges being useless, and, often inaccurate. Here is a case in point.
I was talking to Ed yesterday and he mentioned someone brought a Regal by that was running badly. Guy had just purchased a new rail mounted gauge for more than $30, installed it, and adjusted the pressure to 43 psi. Car ran badly.
Ed put his OTC gauge on the car and found the fuel pressure was 28 psi and not the 43 the gauge was showing. Readjusted the pressure and the car ran properly.
My experience is that even if they read close to right initially, they eventually start reading wrong with age and vibration-liquid filled, or not.
If one goes to Grainger, or similar, the good quality, low tolerance gauges usually sell for more than $100 for a bare gauge.
Further, if one thinks about it, a rail mounted gauge does absolutely nothing for tuning. If you want to adjust your fuel pressure, the O2s and the BLM's will give you all the guidance you need to set the idle. You don't need a gauge to do that.
The principle thing a gauge is good for is to monitor fuel pressure at boost to insure the two are in lockstep. If one is running on straight gas, the O2s will show you when there is a major drop off, but, if one is running alky, it may not be as obvious. Also, monitoring wot pressure will often allow you to catch a problem when it is still small in magnitude which O2s do not yet reflect, or which is being covered up with alky. This requires a gauge that can be read while driving. Having a gauge on the rail is only good for impressing the kids down at the Sonic, or the Wawa.
Take that $30 and go buy a lap dance. It will do more for you.
