Fuel Tank pressure build up

[CHROME~TURBO]

Got a new VP-44 pump and the up dated FASS lift pump installed in my 2000 Ram 5. 9L. It seems there is a lack of power from what was there before. Along with a bit of a hesitation on full petal to the floor where before it would move right along. Just does not feel all the power is there???

So the other day I went to get fuel and when I took the fuel cap off there was what seemed to be a LOT of back pressure in the tank a good pufffff sound. If I keep the fuel cap loos it doe not built up so much is or could this just be the difference in the new VP-44 / new FASS set up?

ANY HELP? Got to take it back to the shop next week but just wanted to see what ya. ll might say.

THANK YOU. .

 

[NavyDood]

Your vents aren't clogged on top of the tank are they?

 

[CHROME~TURBO]

Don't think so , keep truck pretty clean in-out-under. Worked good until the new stuff was put on. Thank you

 

[Motorhead]

You might get better results by moving this to the second gen 24V forum.