Fuel pressure Guage utiliziling diaphram

[litz]

Anyone used the a mallory or other Fuel pressure guage in their car which utilizes a diaphram under the hood connected to the fuel rail which keeps fuel out of the car?

basically the diaphram has a fuel line running to it from the fuel rail, then from the diaphram a second line filled with antifreeze goes to the gauge in the car. How accurate is this set up? Anyone have comments, good or bad?

 

[gofstbuick]

I have a autometer fuel pressure gauge in my Chevelle. It has an isolator in the engine compartment so I can view fuel pressure from the cockpit. It is accurate and works very well. Some of the newer systems use a electric sending unit. It is my understanding, that this system is more expensive than the mechanical unit that utilizes an isolator.

 

[litz]

when you say accurate, how to you know? I mean do you have a guage on the rail to compare it to or have you hooked up a test guage to the rail for reference, and if so, what kind of differential do you see, 1-2 lbs or more?

I am thinking of getting one for $25.00 bucks from a guy, it is in great shape, but have heard mixed stories about accuracy. Heard if you want accurate you need to spend $200 for an in car guage.

I would like to be able to see the pressure as I go into boost.

 

[salvageV6]

I've got the autometer one with the isolator.

Hard to install but once it's in there it worked fine for 3 years.

Now it seems a couple of pounds high compared to a good reference gauge I use on the fuel rail. Could be an air bubble near the gauge or isolator I'm not sure.

Can't do static adjustments easily with the incar gauge cause it's in the car lol.

Anyway I like mine and it's always good to see it move upwards under boost.

 

[gofstbuick]

Originally posted by litz
when you say accurate, how to you know? I mean do you have a guage on the rail to compare it to or have you hooked up a test guage to the rail for reference, and if so, what kind of differential do you see, 1-2 lbs or more?

I am thinking of getting one for $25.00 bucks from a guy, it is in great shape, but have heard mixed stories about accuracy. Heard if you want accurate you need to spend $200 for an in car guage.

I would like to be able to see the pressure as I go into boost.

We're not talking about turbo/fuel injection pressures on my Chevelle because it's carbed. I have compared rail readings to cockpit readings and they're within range. But my range on the carbed engine is 6-9psi. That is mechanical fuel pump spec and that is what I'm seeing on my gauge. I'm just commenting on the gauge in my Chevelle. If it's accurate for my carbed engine, I figure if you install a gauge that reads FI pressures, it will be accurate. There isn't much difference in price between the mechanical gauge that reads 0-15 psi and the one that reads 0-100 psi (45 as opposed to 48). If you don't think it will be accurate enough for you, try the electrical gauge with the sending unit. The prices have dropped considerably (almost to the price I paided for the unit with the isolator)