So as the title reads, my car won't start unless i have my foot on the gas.I don't need to floor it just the slightest ammount starts it. Then with the pedal down it runs (slightly rougher than usual), but as soon as I take my foot off it stalls.

Specs:
1987 Z28 Camaro
305 TPI (LB9 I believe)
Flowmaster cat back
fuel pump replaced about 4 yrs ago
brake lines replaced a couple weeks ago due to a leak from rust
battery replaced about a week ago
O2 sensor replaced 2 days ago

It's done (what seemed like this same thing) before ever since I got my exhaust on. It would happen when vapors would build up in the gas tank (possibly from the heat of the new muffler too close to the tank?? i dunno) but usually i would just let it cool off and take the gas cap off for a second to let the pressure out then it would start up fine and run fine.

This time however it's completely cool barely any pressure came out of the tank and it still wont start so I'm not sure if it's a completely new problem or not. I tried adding some dry gas thinking it was moisture especially since it was sitting all winter, but it didn't help. I'm worried it's the fuel lines (since the brake line bundled with them was leaking a while back) I can't check for leaks now cuz it's raining pretty heavy, but I couldn't smell anything tho. would a fuel line or pressure in the tank do this? any ideas?

 

have you checked your idle air control valve? it may be stuck or clogged.

 

no, but I'll check that in the morning thanks

 

Also check your fuel pressure at the schrader valve. Stock should be about 42 with vacuum line disconnected from the regulator. Especially check it while cranking to make sure it isn't dropping off when the load of the starter pulls battery voltage down low.

I tend to doubt that's the problem, but it's one of the big 3: fuel, spark, compression.

 

...wow, I knew it would be something dumb apparently when they replaced my O2 sensor they must've bumped one of the spark plugs. The boot was on but not "clicked". I remembered how close that sensor was to the plugs so i just made sure they were all pushed on and then it started right up. Thanks for the help tho guys I'm glad it was nothing.