Fuel pressure question

I don't know if this is something to worry about or not. But I have a fuel pressure gauge coming off of my Holley regulator with vacuum port. It reads 7psi at idle if I rev it up it drops to around 3. The regulator vacuum port is going to the base of my E85 SV1. I have one side of the regulator going to the carb and the other going to the the fogger system. Overall the car is running great but I want to spray it soon so I was just going over things and found this. I have a Magna Fuel 500 pump. Will it make a difference between the car being in Park vs. WOT with a load? Or maybe I just need to try a new pressure gauge? I thinking I need to get a new gauge for in the car. Thanks in advance, for any insight.

-Jeff

blu69MachI wrote:I don't know if this is something to worry about or not.  But I have a fuel pressure gauge coming off of my Holley regulator with vacuum port. It reads 7psi at idle if I rev it up it drops to around 3.  The regulator vacuum port is going to the base of my E85 SV1.  I have one side of the regulator going to the carb and the other going to the the fogger system. Overall the car is running great but I want to spray it soon so I was just going over things and found this.  I have a Magna Fuel 500 pump. Will it make a difference between the car being in Park vs. WOT with a load? Or maybe I just need to try a new pressure gauge?  I thinking I need to get a new gauge for in the car. Thanks in advance, for any insight.

-Jeff

The mallary I had with the vacuum port was not vacuum activated it was boost activated. Mine would do just like what you are saying yours is doing. Pull the vacuum line off the carb with the engine running try blowing in the vacuum line and see if the pressure goes up, if it does then it is a pressure activated. I just left the vacuum line unhooked and set it at 7.5psi I was running a1050 alky carb on my 552 without any problems.

I started the car and gave it a quick rev and it dropped again. I blew into the hose and it pretty much stayed the same. After blowing into the hose, I reconnected it and revved the engine and it went up. I notice the gauge ticking up and down so I tapped the glass and it dropped, tapped it again and it went back up. I think I need to get another gauge for sure. I appreciate you dropping your knowledge on me, thanks!

Never heard of vacuum to the fuel reg ? As mentioned only connected and used if running boost. Product engineering use a little sintered bronze breather to block the hole if not using boost

The vacuum port causes the regulator to increase fuel pressure for WOT.

blu69MachI wrote:The vacuum port causes the regulator to increase fuel pressure for WOT.

Ok Thanks . Never come cross that before

What regulator do you have?

It's a Holley I got it from Pro-systems with the Carb.

You should call Pro Systems with your problem. Doesn't sound correct to me

My fuel pressure gauge turned out being bad, everything is working the way it should.

Good. Do you have anymore pictures of the car posted somewhere? Looks nice.