Im getting bad gas mileage....need help figuring out the cause

i had the fuel pump go out awhile ago and on that tank of gas its gotten worse ever since. Im gonna do a tune up with new plugs and wires but im afraid of ruining the new plugs if im running rich. thinking it might be the o2 sensors and i might replace those too. but im not throwing any codes for them.

My question is how can i tell if im running rich and/or wats causing the bad mpgs?

I also am running an open y pipe....dunno if that matters at all but just throwin it in there.

http://img241.imageshack.us/img241/650/1000082ts8.jpg
http://img167.imageshack.us/img167/3814/1000081ca3.jpg

the old plugs how do they look? looks like they might have some oil on the threads and the tips are fairly black. they are bosch platinums btw. can you tell by this if im running rich.

i had the fuel pump go out awhile ago and on that tank of gas its gotten worse ever since. Im gonna do a tune up with new plugs and wires but im afraid of ruining the new plugs if im running rich. thinking it might be the o2 sensors and i might replace those too. but im not throwing any codes for them.

My question is how can i tell if im running rich and/or wats causing the bad mpgs?

I also am running an open y pipe....dunno if that matters at all but just throwin it in there.

How sure are you that you are getting bad mileage? How much worse is it now? Have your driving habits changed? Are you driving different places now, especially places with more traffic, hills, and the like?

That said if you're running really rich you should be able to see it and/or smell it (it will be black smoke and smell like gas, duh). You can also try pulling some of your plugs and seeing what they look like.

That said, the open y-pipe should NOT matter.

You can also try getting someone to try checking out your A/F ratio and computer.. see what's going on there.

i was getting 200 on a tank before. it went to 180 or so on the tank the fuel pump went out on. now its like 165-170. my driving habits havnt really changed. ive been driving more lately but not up hills or in alot of traffic. i usually try to shift at around 2k sometimes a little more. my driving is also 100% city.

I know those numbers are extremely low but its because my spedo reads about 10mph slower than im actually going.

check out the pics of the old plug i posted.

could it be that i just need a new fuel pressure regulator?

The Y pipe could cause issues depending on how close it is to your O2 sensor. If its close, it could cause it to read lean, therefore inducing the pcm to add more fuel to compensate. I'd close that sucker up, put in new plugs, and re-test it.

Ken R.

omfg how the hell do you get the #8 plug out?!?! Im burned, bleeding, eatin alive by bugs, dirty and soar. Im using a universal joint and i finally got the damn thing on but i cant turn it with the 2 inches of room i have and 1 finger.:mad::mad::mad: ****!

any ideas?

omfg how the hell do you get the #8 plug out?!?! Im burned, bleeding, eatin alive by bugs, dirty and soar. Im using a universal joint and i finally got the damn thing on but i cant turn it with the 2 inches of room i have and 1 finger.:mad::mad::mad: ****!

any ideas?

It would probably help a ton to have a cut spark plug socket, then you put a wrench (preferably ratcheting) over it.