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Author Topic:   Fuel Pressure Gauge
Strokin27
Member
posted May 15, 2002 08:36 PM
My fuel pressure gauge is bouncing so much it is just about impossible to tell what the actual psig is. I have a manual 15 psig pump
with a regulator behind the fuel log. The pressure goes in at the pressure port of the regulator and my gauge is hooked to the pressure out port and the return line comes out of the bottom of the regulator. The regulator is the Barry Grant type with a jet in it. Did I not follow the directions correctly?

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Strokin27
Artie Perilloux


Pickel
Member
posted May 15, 2002 09:05 PM
I run a fuel pressure regulator from Speed Freaks just a little cheapy and a cheap fuel guage and it doesn't bounce around at all. Check and see you might have it hooked up wrong and it might be just flucuating. (In the regulator).

[This message has been edited by Pickel (edited May 15, 2002).]

[This message has been edited by Pickel (edited May 15, 2002).]

fridge
Member
posted May 15, 2002 09:26 PM
are you guys running alcohol, my carb is set up with the gas line running into my fuel log and my regulator on the back of my fuel log with a line running out of my regulator to my fuel cell, and the carb guy says i cannot do this with alcohol, but what i don't understand with or without alcohol i have the same fuel pressure, any info would be appreciated, thanks


bogged
Member
posted May 15, 2002 09:46 PM
if you run a fuel log, tie the line to the gauge in there. The problem you are having is caused by the operation of the regulator. If no fuel log is used, splice the gauge in the middle section of the line from the pump to the carb.


jlfastride
Member
posted May 15, 2002 10:24 PM
artie the claw man. hey here is the problem i had with that set up my pump was a procam 15 psi pump with a bg log that has the built in bypass. what i found was the pump pressure surged real bad at race rpm the pressure was set at 7 psi but at idle the pressure would surge from 3 to 14 psi with every stroke of the pump ran fine but loaded up real bad at idle floats couldn't handle the high spikes of pressure. this year i bought a belt drive pump and everything is working real nice 3 psi at idle and like 8-9 on the gas. so go with the bypass for 200bones or a belt drive pump you will be much happier. gl jlfastride.


Strokin27
Member
posted May 16, 2002 07:47 PM
Is it possible that I have air trapped in the line from the regulator to the gauge?


jlfastride
Member
posted May 16, 2002 09:37 PM
nope if anything that would cushion the guage action.


Strokin27
Member
posted May 17, 2002 09:17 AM
In my line of work we pressure test a lot of piping using water and a pnuematic pump. If there is any air in the system the pressure of the test will not hold due to the fact that the water is continuosly compressing the air. Liquids will compress only so much and build up pressure due to hydraulics, thats why I am contemplating to bleed the line from the regulator to the gauge.

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Strokin27
Artie Perilloux


nvracer
Member
posted May 17, 2002 10:35 AM
It could be the gauge is bad. I would check this first. Before I spent alot of money on other things. Most of the fuel gauges have a isolation diaphram between the fuel and gauge for safety reason. It could be broke.


Strokin27
Member
posted May 17, 2002 12:10 PM
I have installed a second gauge on my fuel log and it does the same thing. Should the pressure to the gauge be in the large 3/8 NPT fitting or the small 1/8 NPT fitting in the side of the regulator with the pressure out fitting plugged?


wfoondirt
Member
posted May 17, 2002 04:25 PM
Are you using a mech or diaphram bypass. With a mech you need to run a mech bypass, the diaphram will have a hard time accuratly controling the pulse from a mech pump.


Strokin27
Member
posted May 17, 2002 08:25 PM
wfoondirt, I think that the pulsation is my problem. I have a BG Diaphram regulator I think. I will disassemble it tomorrow to see just how it all works. I may have it hooked up incorrectly but until I get it figured out I will not take the chance of leaning out an engine due to a pressure gauge problem. I just don't have the cash right now to install the belt driven pump that will solve all these problems. Everything is new from bumper to bumper and I choose not to do something stupid to make a race.

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Strokin27
Artie Perilloux

[This message has been edited by Strokin27 (edited May 18, 2002).]

Strokin27
Member
posted May 17, 2002 08:34 PM
wfoondirt, I finally decipfered your post, from what you are saying is that if your throttle bypass is controlled by your throttle linkage then you need a MANUAL bypass valve huh! If it is not controlled by a manual bypass then you need to use a diphragm controlled pressure regulator.

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Strokin27
Artie Perilloux


WPP
Member
posted May 18, 2002 08:49 AM
ARTIE THREW MY EXPERCES WITH THE BYPASS I RAN A BG AND I HAD A LOT OF TROUBLE WITH IT MY BYPASS WAS FOR A BELT DRIVE PUMP AND I RAN A MECH PUMP WHAT HAPPEN WAS THE PRESSURE WENT CRAZY WHEN I GOT OFF THE THROTTLE AND FLOODED THE CARB . THE FIX ON THIS WAS THE RETURN LINE I WAS RUNNING A 6 LINE AND WENT TO NUMBER 8 LINE FIX THE PROBLEM . JUST GET THE RIGHT BYPASS FOR THE MECH PUMP. IT WILL SAVE YOU ALOT OF PROBLEMS


28 mod
Member
posted May 18, 2002 03:19 PM
well then also you could just plumb a tiny orfice into the guage line and then the guage would be more steady. course the press would still be bouncing like a biltch but hey if all you care about is the guage action then you really don't care about what the press is doing anyways. the bouncing is caused by a surging of the pump. period


jlfastride
Member
posted May 18, 2002 08:17 PM
you really should fix the cause and not just the effect.


Strokin27
Member
posted May 19, 2002 06:16 AM
Well guys I plugged the jet in the regulator
that is plumbed in behind my fuel log and I have both of my gauges calmed down to where they are readable. The regultor doesn't work as advertised but I have around 8 psi at idle without floating the needle off its seat and 10 to 11 psi under heavy acceleration. As soon as I can I will switch to a belt drive and be done with these problems. Thanks

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Strokin27
Artie Perilloux


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