I currently have the Di procol 30lb. fuel pressure guage with a P. O. S isolator. For at least a year now the isolator has been shot, if it's warm outside and I sit for a few minutes the fuel pressure rises all the way to the max, after I get moving it will drop very slowly to normal. I do have fuel at the guage which is not a problem so far. Do I need the isloator? I am under the impression the isolator keeps the fuel from getting into the cab. I am thinking I can just remove the isolator and run without it. I don't see the need to pay for another isolator that will only last about 2yrs. , that's all I got from the original that came with the guage set up.