can some one explane to how the fuel pressure isolator works? How does it do it with out bringin fuel into the gauge?

 

The isolator has a diaphragm in it which separates the fuel side and the water side. You run a braided line from your fuel rail to one side of the isolator. You run another braided line (preferably) from the isolator to the gauge. The side going from the isolator to the gauge is filled with a 50/50 coolant/water mixture to prevent freezing. Since water is essentially incompressible, the fuel pressure seen on the one side of the isolator is trasferred to the other side via the diaphragm and what you see is an accurate indication of your fuel pressure without having a fuel line running inside your car.

Just be aware that, at least in the past, these isolators often times failed... the diaphragm failed. So, you'd end up with fuel in the line going to car I think they are getting better though. I've had one fail on me but the new one is doing good.

 

Ditto what Brent said.

By the time you buy the AutoMeter mechanical gauge, the HIGH PRESSURE isolator, and the braided hoses, you will have spent as much as the cost for the top-of-the-line electronic gauge. Then you have to fiddle with filling the passenger compartment side of the system with glycol, and trying to keep it full, or the gauge doesn't work.

I had an AutoMeter 5280 high pressure isolator, and it FAILED - rubber diaphragm ruptured.... allowed fuel into the lines in the passenger compartment. AutoMeter eventually recalled the 5280 isolator, and gave me full credit for the mechancial gauge, isolator and lines toward their electronic gauge. They also gave up on their 5281 high pressure isolator, which was supposed to be impervious to virtually any fuel. That didn't work either. Now they have the 5282, and for $120, who knows if that one will work. I personally will NEVER put a mechanical fuel gauge inside the car.

 

Yep, I have to agree with Fred about just getting a good electronic fuel pressure gauge/setup.

I have purchased the Mallory isolator for use in my 96SS (not yet installed... pretty much like everything else I buy) and will be very cautious with it. I've got nearly $200 in all the stuff and for that you should be able to get a damn good electronic gauge.

In the past people didn't care much for the electronic gauges because they didn't respond fast enough or accurately enough. I do believe the newer higher quality electronic fuel pressure gauges are much better and respond almost identical to a mechanical gauge (or so I've heard... I have yet to see one for myself!).

 

I'd also suggest an electric version if you're thinking about an isolator.

Summit Racing sells them for $186! I have their model 3363, and it works great! Only thing coming into the cockpit is electricity.

 

#3563 2-5/8" here and it works fine... very rapid response to fuel pressure changes.