IHADAV8.com - Turbo Buick Tech, and Nonsense

Tech Area => General Buick Tech => Topic started by: Steve Wood on July 15 2012, 04:57:12 PM

Title: Fuel Pressure Gauges
Post by: Steve Wood on July 15 2012, 04:57:12 PM
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.
Title: Re: Fuel Pressure Gauges
Post by: phil_long on July 15 2012, 11:39:19 PM
Nice
Title: Re: Fuel Pressure Gauges
Post by: smokin-6 on July 16 2012, 07:35:22 AM

Take that $30 and go buy a lap dance.  It will do more for you.

 :rofl:
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 16 2012, 09:19:32 AM
Or use that $30 to buy Phil a bus ticket because he knows how to set it without a gauge!
Title: Re: Fuel Pressure Gauges
Post by: phil_long on July 16 2012, 01:00:05 PM
Or use that $30 to buy Phil a bus ticket because he knows how to set it without a gauge!
That's right.  Im officially a step higher than a noob!! :rock:
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 16 2012, 03:05:17 PM
much as we beat you up, you are too well used to be a noob!
Title: Re: Fuel Pressure Gauges
Post by: phil_long on July 16 2012, 03:47:28 PM
This is true
Title: Re: Fuel Pressure Gauges
Post by: Scott87 on July 16 2012, 04:29:00 PM
Any chance you have a model number you could suggest?

Posted From Tapatalk
Title: Re: Fuel Pressure Gauges
Post by: daveismissing on July 16 2012, 06:03:41 PM
Mcmaster.com  3795K16
subject to approval :)
- gasoline rated, glycerine filled, four inch, ss case,  two percent mid scale
Title: Re: Fuel Pressure Gauges
Post by: earlbrown on July 16 2012, 09:02:49 PM
any idea whats the widest tires I can fit on my stock rims?
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 16 2012, 09:22:53 PM
LOL  I think some have run 275s with rolled fender lips...but seems to me that would be a bit squirrelly
Title: Re: Fuel Pressure Gauges
Post by: daveismissing on July 16 2012, 09:43:55 PM
I'm sure you can fit  those 275's weaselly.
Title: Re: Fuel Pressure Gauges
Post by: earlbrown on July 16 2012, 10:38:03 PM
Whats the biggest turbo I can run and how much boost will it push?
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 16 2012, 10:42:15 PM
Do you want to run a hood?  How many times do you wish to push the boost?
Title: Re: Fuel Pressure Gauges
Post by: earlbrown on July 16 2012, 10:48:31 PM
I want the biggest turbo I can fit. I want it to work with true duels and gears.


I saw some hedders on ebay too that look pretty sweet.
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 16 2012, 11:00:41 PM
I would run two T104s and use a couple of 4" John Deere exhaust stacks straight up from the engine compartment with a rebel flag on each one.
Title: Re: Fuel Pressure Gauges
Post by: earlbrown on July 17 2012, 02:02:58 AM
It'll be like a smiley face with my GA state flag on the bumper.



Now about spraying my innercooler with NOSŪ.........
Title: Re: Fuel Pressure Gauges
Post by: ULYCYC on July 17 2012, 07:45:43 AM
I want the biggest turbo I can fit. I want it to work with true duels and gears.


I saw some hedders on ebay too that look pretty sweet.

First you need a 3/4 race cam and hook those headers up to chrome lakepipes. :icon_eyes:
Title: Re: Fuel Pressure Gauges
Post by: Steve Wood on July 17 2012, 09:04:52 AM
After lakepipes, I remember the fad was to take two driveshafts and cut the ends off them leaving the hollow tube.  We then attached them to the exhaust where it came out of the engine compartment and let them hang under the car.  Of course this eliminated mufflers and such.  I wish I could remember what we called them...other than loud
Title: Re: Fuel Pressure Gauges
Post by: ULYCYC on July 17 2012, 09:29:56 AM
I remember seeing that but no clue if it had a name other then pure innovation. That's whats lacking today
Title: Re: Fuel Pressure Gauges
Post by: Scott87 on July 17 2012, 01:12:14 PM
This thread is now delivering.
 
Thanks Dave will see about getting one of those from McMaster.
 
Title: Re: Fuel Pressure Gauges
Post by: granitestategn on July 22 2012, 01:05:39 PM
One caution about liquid filled gauges. I like them because they dampen the vibration that can kill a gauge but.........
 
The liquid filled gauge housing is sealed, otherwise the liquid will leak out. The problem arises when the gauge body see a temperature difference. Since the gauge is sealed, the pressure inside the gauge body can (and will) change with a change in the temperature of the gauge. This can cause an errror in the reading that can be pretty significant. I have seen errors of over 5 pounds in an industrial envirionment. ALWAYS burp the gauge before using it for reference work (like setting base pressure). There's usually a black rubber push-in seal or sometimes there a plastic vent lever built into the seal. If the gauge is installed upright, the vent lever is best left open. If the gauge is attached to the end of a hose, leave it closed and burp it with the lever before reading it.
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