I have lost a significant amount of gas mileage in the last couple weeks after replacing my fuel pump and filter. I was getting 19/29 now I am getting 10-12/19. I have a 99 trans am a4. Thanks for any help

 

I lost a significant amount to after I installed a trex and all my bolt ons

But seriously, it sounds like you have a leak. Put some cardboard under your car when you park it at night to see if any fuel leaks right under where you installed the filter.

 

thanks that is a good idea but i have also performed a leak-down test on the whole system and nothing has shown up on it ... By the way it is a stock gm fuel pump

 

ttt..

 

If you aren't leaking there is no reason you have lost mileage.

Keep track of it over the next tank and see if your low mpg repeats itself.