I have an 83 Z28 with the Crossfire 305. It has a terrible hesitation. When i take off from a stop or try to give it some serious gas while driving it hesitates. I have changed fuel filter, O2 sensor, plugs, plug wires, ignition module and coil. I have taken it to a shop and the guy told me that it came up running lean but that everything that he checked was fine. Other than hesitation it runs fine. The hesitation is worse after it has been running for a while. After changing coil and ignition module it ran fine for a few days then hesitation came back. It does seem to knock a little when i first start it up after it has been sitting overnight. Every once in a while the check engine light comes on for a few minutes. Any help would be greatly appreciated! Thanks!

 

If you're gettting the check engine light a first step would be to check the computer for codes. If you don't know how ask and I or someone else will tell you...it's actually a simple procedure.

 

I don't know how to check for codes but if I remember right the guy at the shop that I took it to said that it was coming up with a lean code (don't remember number) I think. Sorry not the smartest guy when it comes to cars! Thanks!

 

Well to check the codes, first you have to take a paperclip and bend it and jump out the computer diagnostic connector. This is the connect by the driver's right knee in the hush-panel. Use the paper clip to jump out the two upper-right most connectors, and turn the key to the run position (but don't start the car,) and count how many times the light flashes. You'll get three code 12's in a row, the computers stores codes, and three more code 12's to let you know it's done. You can tell its a code 12 because the light flashes once, a small pause, and then twice. Same thing to check other codes... long pauses represent a new code and short ones represent the difference between 10's and 1's in the code.

 

I check the codes and it came up a code 13 whatever that means!

 

Get a service manual and check what a code 13 is. Or call a car parts store, some of them can look it up and tell you what a code 13 is. I don't remember off the top of my head what code 13 is, and I don't have my service manuals at work. I just called a local parts store, and they said 13 was a lean condition. Since you replaced the O2 sensor it is probably one of the ideas below.

Check the injectors to see if they have a fine spray coming out. If they kind of drip instead of spray, or spray very little when you rev it, you probably have a clogged injector. If all of them have a problem, I would lean towards the fuel pump. The best fuel system cleaner I have used is Castrol Syntec fuel system cleaner. Run the tank as close to empty as you can. Add the cleaner with a tank of super unleaded and run it through.

Another possiblity is the fuel pump may be about ready to die on you. I changed the fuel pump on my buddy's 84 Vette with Crossfire injection last year. On the Camaros, you have to drop the gas tank to replace the pump. It is an electric pump inside the tank. The pump may still be working somewhat, but it may be getting weak and not supplying enough gas. A new pump will be about $40-50, and make sure you get a new strainer if it is not included with the pump. The strainer goes on the end of the pump that sucks the gas from the tank and prevents any chunks of stuff from clogging the pump. They are usually under $5. These are 2 possibilities, that both make sense with the fact it is running lean. Good luck.

 

Ok i have decided to change the fuel pump. Any suggestions on ways to make this job a little easier. My dad (aka my mechanic) told me that maybe we could pull the carpet in the hatch back and cut a hole in the car to get to the fuel tank a little easier. Rivet the metal back on afterwards and put the carpet back over it. Just an idea. Any help would be greatly appreciated!

 

DON'T CHOP UP YOUR CAR! Take the fuel tank down and do it right.

That is, IF the fuel pump is even causing the problem. A $40 pump sounds pretty cheap, I paid more like $90 (for my Bonneville - perhaps the TBI pumps are less expensive).

Not sure what order you did all these things, or if the hesitation existed before or came on after these parts were changed out. But, when I got a lean O2 sensor code, changing the sensor fixed it. It's not outside the realm of possibility that you got a bad sensor. I'd change that $25 part before going through the hassle of changing the pump.

By the way, the trouble codes are listed on the FAQ link on this board.

 

I don't know what a code 13 is specifically. However, if you are running lean and have changed all the parts you mention in your post, then I would check to make sure your TBI's are synched correctly. If I remember correctly the process is a little drawn out, but once you get it done and done right the hesitation will be gone. Check a shop manual for the procedure and what tools you will need......

 

code13=Oxygen sensor signal problem or loss :lala:

 

Just be careful in case you do decide to cut the hole in the trunk (which I also would advise against...) the clearances between the trunk floor and the top of the tank are tight... in other words-don't cut into the tank or you'll be swapping out a bit more than a curse if ya don't blow the thing up!