I just put the fass system on my 01 and i am very unhappy with it . I lost 3 mpg total and it seems like my truck is slower than it was with stock pump.

I got this due to recommendation and testimonials by everyone and it seems to be not all that. Anyone have the same relation?

 

the having is greater then the wanting....sorry....imo the fass is a pos.

 

What are your fuel pressures? I doubt the fass is causing your mileage drop. Why did you switch to it?

 

Post up mi amigo. I may be just a couple of days from getting one. PM if you want. I want all the real world opinions I can get on these systems....pumps in particular...from both sides of the fence.

 

Your not going to lose power with a fass compared to stock, losing mileage is possible but it's likely it's just fueling better and the skinny pedal is down more. Run a few more tanks through it. You likely have other issues, VP44, bad fuel, lots of other possibilities. I noticed a slight drop in mileage too but I blamed it mostly on my driving and the 275's I added at the same time. Run some more fuel additive too and give it some time. I was happy that the fass pump cleaned up my exhaust alot at startup.