Why is my fuel pressure gauge shacking?

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Moparornocar51

Moparornocar51

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Hi guys i just made a short vid where you can see that my fuel pressure gauge is shacking, before i had one from allstar with glycerin and the one died now i have one from russel performance but its the same thing, could it be that i have some leaks up the lines? My car drive good without any problems, just wanna fix that

Thx Peter

[ame="http://www.youtube.com/watch?v=xAofJcGvIq0&feature=youtu.be"]MOV00374 - YouTube[/ame]
 
likely if your still using the manual fuel pump its from the surge when the pump "pushes" the gas upto the carburator

electric you don't tend to see that
 
Thx for the reply but if its the mechanical fuel pump it should never worked before, but few weeks ago i had constant 7 psi on my fuel pressure gauge and it worked just fine
 
Mine is steady until I start getting some fuel boiling (primarily from today's fuel mix). A regulator cannot regulate the gaseous state of gasoline and will show as a fluctuating gauge.
 
From what you said, i believe the regulator may be the culprit. I'm not sure with a regulation mechanical pump and a Holley that you even need a regulator?
 
i have a regulator after my electric pump and before my mechanical. my fuel pressure gauge will pulsate when my electric is off, when i switch it on, my gauge is rock steady.
 
I had an Autometer and it would run smooth with the electric pump and when it ran on just the mechanical pump . Had the regulator set at 5 lbs . Maybe your mech pump does not put out enough pressure ? What's the regulator set at ?
 
A mechanical pump builds pressure from the internal spring, pumps up pressure, and for a second/ few seconds after the needles seat, the pump are "floats" and the pressure should be VERY even.

I would guess you have dirt in the pump valves, or in the regulator that is allowing some leak--back.

You run an electric before the mechanical? Might try bypassing the mechical and see if this changes.
 
Hi guys i just tried a electric fuel pump on my old 318 now i have a stroked 426 from hughes and i used this pump http://www.racepumps.com/tech.html, the first time when i start my engine i adjust the fuel pump regulator at 7psi and it worked well then the gromet from my old gauge was damage and i loss fluid now i have a new gauge from russel but as you can see it dont show me the real pressure i will try to clean this stuff first and will let you knew what i find out thx Peter
 
Do you have a way to temporarily isolate that gauge from where it's mounted - as a test? Engine harmonics (vibration) could be at play - especially if it's not liquid filled.

Just went through this with my blower motor. Before I installed my hood I had an Autometer fuel pressure gauge mounted at the back of the blower where I could see. It was steady at idle and even cruising until you hit 45 mph or so. Then it would start fluttering just like yours. I wondered if it was a fuel pump issue too.

Well, I got on the gas one day entering the highway and it fluttered so violently it took out the gauge. I talked to a service tech at Autometer and he was sure it was engine harmonics that did it. When I finished my hood and moved the gauges from the back of the motor to the hood, the problem was solved.
 
Let me add , my meter ws mounted on the hood , not motor , maybe that is why yours shakes , like 70 duster440 said
 
Can you guys show me some pics where you put the gauge on the hood and how? thx Peter
 
I have a large hole in my hood :)

People mount them on the hood, on the cowl, or inside the car using a gauge isolator (you don't want a mechanical fuel pressure gauge inside the car for safety). If the gauge is on the regulator, some people mount the regulator on the inner fender.

Have you tried moving the gauge off the engine to see what it does? If it is engine vibration, then the cheapest thing would probably be to buy another small liquid filled one.
 

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thx for your answer yes i think so too, that a liquid filled one will help me with my problem because it worked before fine too, if not i can sell it and have to find out what my problem is! Thx Peter
 
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