I noticed when I went to fill up that I had a good amount of pressure in my tank is that normal or bad thanks

 

If your fuel cap is not allowing air in to your diesel tank, it will create a vacuum. A vacuum is not something that you want to build. Vacuum will make your fuel system pull harder to get the same amount of fuel out. This could lead to power loss, and other strange fuel related problems.

Most easily it is detected when you have a full fuel tank. This will give you the most fuel, and the least amount of air space. These conditions will tell on you the best.

Say, after fueling go down the road, and then pull off after a few miles. Unscrew your fuel cap. Do you hear a good 'hhhuuushhh'? Chances are you've got a fuel cap issue.

Tanks that are only 1/2 full or less may not be as easily to tell either. The vent in the cap maybe allowing little amounts of air in, but not enough to keep up with the fuel demand.

hope this some to you and if do need new cap make sure it for diesel

This what did to mine

I bought the same fuel cap from autozone and had the exact same problem. Still whoooshed like the old factory unit. So I simply took my dremel and cut out the plastic center of the factory cap and then used some needle nose pliers and removed the valve and spring. I then used a round dremel sander and cleaned up the center portion where I removed the plastic and used compressed air to make sure nothing was left in the cap. Have not had any more issues with whoosh sound full or half full. Took me all of ten minutes to do

 

good advice ^^^