My 95 z28 will almost always die right after it fires the first couple times. After a couple tries it will fire and stay running. Sometimes it will stay running but seem to be misfiring or just running rough so I turn it off and start it again and it will run fine. The whole problem is getting it to start. Once it starts up and stays running it runs good. I want to try to get it figured out myself otherwise this week it has to go to a shop because its my daily driver and I can't have it not starting. Not sure where to start. I am hoping it could be something easy like a sensor or maybe the ICM?

 

Is it always hard to start, or is there a difference depending on whether the engine is warm or cold, or how long since it was shut down?

Does it seem like it's flooding? Have you tried putting the accel pedal to the floor and holding it there while you try to start it? That puts the PCM in "clear flood" mode, and would indicate it is a flooding problem.

You can also check a couple of things. Check the fuel pressure when the pump primes (don't start engine). If the pressure drops rapidly on pump shutdown, it will be harder to start. If this is the case, cycle the key rapidly 3 or 4 times to prime the pump before you try to start it. That would confirm a problem with loss of priming pressure.

Then there's the possibility that the coolant temp sensor for the PCM (in the water pump housing) is faulty. That would show up as a difference in how hard it is to start depending on whether the engine is hot or cold.

 

I forgot to mention that the low coolant light comes and goes daily. It will turn on and off at random. I just replaced the sensor and its still on. Not sure if that means anything or not.
It definitely is easier to start when the engine is still warm. If I run into a store and come back say an hour later it will normally start right up first or second try. When I came out to it the other night around 3am when it was freezing it took me 10-12 tries to finally get her to stay running. It had sat in the cold for about 10 hours.
I have already replaced the coolant temperature sensor along with the water pump and thermostat so I can rule that out.

 

The low coolant sensor only connects to the light on the dash. Has nothing to do with how the engine starts or runs. If you replaced the sensor and it didn't fix the problem, check the wiring.

And the coolant temp sensor you replaced was the one in the water pump housing? Have you checked it for codes? Could be a wiring problem with the sensor.

Flooding is also a possibility. If there is a leaking injector or two, or the fuel pressure regulator is leaking into the vacuum line, the initial drips will evaporate from the heat, but once the engine cools down, the drips are going to stay liquid and cause flooding.

I would definitely check the fuel pressure as described above.

 

Yea I replaced the sensor in the pump, and still have the same problem. About a month or so ago I had it scanned and was told the only thing it was throwing was a injector circuit code. Not sure of the actual code, they just told me.

If I pull off the vacuum line to the fuel pressor regulator will that tell me if its leaking by whether or not it is dry or wet inside?

Also where do you hook a fuel pressure gauge up at? I am going to try and get one.

 

Well I answered my own question on how to hook up the fuel pressure gauge.

Since I have a new fuel pressure regulator, that was given to me awhile back, just sitting around I am going to go ahead and throw that on tomorrow and go from there. I was talking to a couple guys today and from what I was saying was happening they both told me its the fuel pressure regulator. Hopefully that will cure my problem so not only my car will be fixed, but also I wont have to spend any money for the repair. Man would that be nice haha.