My air pump locked up and broke the belt recently. I have been driving it like that for a couple weeks because I haven't gotten around to replacing the air pump. I have noticed that my MPG has gone down drasticaly. Could this be related to the air pump not running?

 

bump

 

I'm not going to say anything is 100%, but in my experience, no, it's not going to effect anything. I removed mine and had no change in mileage.

 

This should not have a noticable affect on your milage. I have read about a 100mv offset in your o2 sensor, that is programmed into the ECM to make up for the fresh air being pumped into your exhaust, therefore it could affect your A/F ratio However, 100mv is a VERY small amount. Furthermore, it only comes into play during certain, uncommon driving conditions. I would start looking for a leaky injector or something else. Good luck.

 

Buy, borrow a working pump see if mpg goes back up and let us know. Mine was removed prior to me, and mpg are 15 town 20 trip with a stock OEM chip.

 

If you look for air pump delete you will get MANY opinions on the subject. I removed my air pump for thae same reason you did and it didn't affect my gas at all. It maybe even went up just a tad. Motor wasn't turning an old half frozen pump. I went a step further. I installed the Hooker headers/Y-pipe and now my engine-bay is SO much easier to work in without all the tubes and diaphams...etc. Best money I ever spent. MPG was 21MPG with 5.0 tpi and after swapping with 5.7tpi from same year GTA into my Trans-am and pulling the air stuff off, I now get 20mpg. Luckily I live in Michigan and don't have to worry about smog test. It seems the 20 mpg. is what people here are getting with the 5.7 and alittle better with 5.0. Make sure you routed belt correctly and water pump turning oppisite of everything else. I also swapped my motor because I had starting problems. Found my injector coils read from 2 ohms to 12 ohms.(should be all the same) That's a quick check to see if they are O.K. electicaly..BTW.