Any ideas on what to fill the plastic tube with from the isolator to the gauge? I got a syringe with gauge, but it won't fill fully and takes multiple refills the fill the line. Each refill introduces air into the line. I'd like to figure out a way to fill and flush the line of air without refilling. I'm pretty sure that air in the line is causing an exaggerated reading of low fuel pressure.

 

Well being I don't work with isolators...

But if a person was to want to purge the coolant side you would have to have a small amount of pressurized coolant and plug in at the fill port and loosen the other end. Adding pressurized coolant to the system till the coolant leaks out at the gauge. Tighten your fitting. Then add a bit of pressure and release. Plug it and you should be ready. You could most likely setup a garden sprayer for something like this.

Crazy idea...

 

Use anti freeze

 

Does it magically just install itself in the tubing?

I can see how the opening question was not clear. I was asking how to fill it whether than what to fill it with.

 

You will never get all the air out. Mines the same way and it works as it should.

 

Unhook the line from the isolator and use your mouth to suck the fluid up to about an inch from your mouth and hold it there while you hook the tubing back up, then you can fill it the rest of the way with your syringe.

 

I like the idea of eliminating the isolator. Diesel not that flammable anyway.

 

But it makes a mess and I don't want raw diesel spraying in the cab of my truck. That's why I bought and electrical setup for the other truck

 

Didn't think about suction. Maybe RV antifreeze. Non toxic and tasteless.

 

Don't get it in your mouth