I havent a whole lot of work on cars this is actually the first motor practically that I have worked on, I figured the best way to learn is to get in and do it.
I have a 95 z28 that I did the 383 stroker, LT4 heads, LT4 intake manifold, LT4 hotcam for the main stuff. I cant get her to start. She turns over fine, and sometimes will start but then immediately die, however, sometimes she wont even try to start. I had the shortblock assembled professionally. I had them replace the timing chain as well. All sensors are plugged in minus the temp. sensor which I had bought a aftermarket temp gauge.
She was reading about 43psi of fuel pressure when I start it and with key in ignition it shows about 30psi.
I did get her to start with giving her gas and run for about 10 secs, however I didnt have a waterpump hooked up so I shut it off. Then we tried again and she started until I stopped her. Then I put everything on and now she wont start. It sounds like she is close, but sometimes it sounds like it isnt even close at all.
She does have spark and she does have the fuel. Alot of people say timing, but isnt the timing set when the chain is put on??
I have had people say that for her to start I will have to reprogram the ecu mainly because of upgrading injectors. I dont see why I would have to for that?!?
If anyone has any imput on this I would really appreciate it.

 

you have the temp SENDER or the temp SENSOR unpluged?

It will not run correctly with the temp sensor unhooked. it might run, it might not..

 

well it doesnt even start up and i have a aftermarket gauge in there so the factory sensor isnt hooked up but.....

 

Just like HBH said,
The ECU needs the coolant temp information in order to give the engine a proper amount of fuel to start. You need the SENSOR, but not the SENDING UNIT.
Kevin

 

does the sender have any effects on spark? I did an opti and electric waterpump install and now my car won't start. It will turn over, but there is no spark. I pulled it apart and triple checked the opti twice now. Help me please! I don't have a multimeter here and I wish I did. I just need to get my car back on the road.

 

Oh yeah..the reason I ask that is because I was working on the car here at the shop. (I work at a machine shop) and since i was doing the electric pump I decided to glass bead the waterpump housing and said "Heck, would it hurt to hit the sensor to clean it off too?" I don't know if my glass beading has any effect on it. I didn't hit the electronics just the brass part.

 

that is not your problem. I have seen cars start with no waterpump on just to check to make srue it would fire during an opti swap. Sounds like you may have a bad opti or coil... maybe even the ignition control module next to the coil.

 

The opti is brand new. OEM AC Delco and I had no problems before with ignition problems I just decided to change it out while i was doing the pump. Could it really be that conincidental that this happened now? This is my first LT1 and I am learning as I go, but I was careful to put everything back in its place and not forget to connect any wires, sensors, etc. I dunno where to go from here. The car is not somewhere it can stay for very long so I don't know what im going to do if I don't fix it today.

 

Hi,
Your Opti could certainly be bad...even though it's brand new. I have gotten some bad Optis from AC Delco here lately. The first one would fire the coil, but not the plugs. It's as if the rotor had been left out. The second one would let the engine run, but the timing seemed to be approximately 40 degrees advanced. I'm gonna try the third new one this week.
Kevin