Hello to everyone on the forum, my name is Kyler, I'm 18 years old and from Manitoba Canada. Last week I purchased a 93 z28 and I love it to death, it's a 6spd, 165,000 km's, BBK headers, straight piped with a Flowmaster exhaust and has a K&N intake. The car is in very good shape and has ran excellent up until a couple days ago, last night when I turned the ignition the car would barely start up and once it did the idle would go down and stay at around 400-500 rpm and be on the verge of dying. Me and my buddies weren't sure so we through 20 bucks of 91 octane in and it started up fine, we had assumed the fuel guage was off and it was just running right low.

Well when I woke up this morning to go to work I went outside and to my surpise she wouldn't crank at all, so I put the gas down as it was trying to ignite and it went but kept dropping down and staying at around 500 rpm again. I can still drive the car but it backfire alot more then normal when letting off the throttle and won't idle up past 500, Im a little worried and would like to determine the issue.

and ideas come to mind for anyone?

 

I was also going to add that whenever I remove my gas cap theres alot of pressure built up and bursts out when taken off. probably bad? I'm a bit of a noob here but I just want the car running very well as it's in good shape and I want to take good care of her

 

I might have posted this in the LT1 section, you'll probably get more help there. But it SOUNDS like fuel pump is bad. The hissing sound is nothing to be worried about though, it's normal. I would give the car a full tune-up: plugs, wires, fuel filter, air filter, all fluids, everything. You'd be surprised how it runs.

 

does the SES light come on?

 

The pressure in the gas tank could be a missing heat shield (the dreaded dead fuel pump) that was not replaced when the gas tank was removed. Mine had a similar problem when hot as it would boil the gas in the tank.
Just something to look for.

 

many things it could be

did you run the car for a while with less than 1/4 tank in gas??

how long did the car sit before you bought it, could it be some bad gas, if so fill it up with super and fuel injector cleaner or fuel stabilizer

very hard to diagnose over the net

1) any SES/codes?
2) lots of fuel in tank/fuel pressure????
3) fuel filter
4) charged batery???? low volts can play tricks on whole system
The above is where I would start

 

I have ran with les the a 1/4 tank but not for more then a day or two, from what I was told the car had only been at the dealer for a few days before I bought it, although the previous owner could have had it sitting. Im going to a local garage in my city and get them to take a look at it.

Im going to store the car for winter which will be within the next month or so. Im thinking I'll wait till spring to change all the fluids, filters, plugs etc.

I guess it's hard to get a good figure because no one here can actually see the car but any ideas on how much a full tune up would be at my GM dealer? Im guessing alot but i'll have the winter to save for it.

also thanks for the help and suggestions, I appreciate it