I have read about some people installing fuel pressure gauges on their diesel trucks in the cockpit area without fuel isolators. With a gas engine, that would seem to be a risky,if not unacceptable proposition.
Maybe I don't respect the flamability of diesel enough, but with a diesel truck; it just doesn't seem like that big of a hazard to me. Anyone have an opinion on that?

 

I agree, I wouldn't do it with a gasser either. But I'm running a mech. fuel pressure gauge in the cab, no isolator. I just got some stainless steel braided hose with -4an ends for piece of mind.

 

You have to dampen the flow to the gauge on a 12 valve or the needle will pulsate so wildly that you can't read it in the short amount of time before it self destructs. This is done with a needle valve closed almost all the way or a gauge dampener.
I've disconnected the line to the gauge with the needle valve in it's adjusted amount of closure, the amount of fuel that came out with the engine running was nothing more than a slow drip.
Not a major deal if it were to leak and besides you could shut it off with the valve.
You have to remember there is no flow from the engine to gauge when it's hooked up correctly, just changing pressure.