i recently finished up my lifter and cam swap, and when i got my car all put back together it started up just fine. i let it run for a while and then changed the oil and then fired it back up again. since it was running very rich i hauled it to get the exhaust put on. when i got it home i had started it four or five times just working on various things, and now all of a sudden it will not start. it just cranks and won't fire. i have no idea what is causing this. i have pulled all of the plugs and checked them, i put a new fuel filter on it, i have double or triple check my plug wires. i have no idea what to do next. anyone have any suggestions? and yes it has gas in it.

 

Do you have fuel presure and spark? Did you forget to plug anything back in, coil plug, MAF, ect..?

 

i had already started it like 6 or 7 times after i got everything back together. it started one day and the next it didn't without changing or unhooking anything

 

When you changed the fuel filter you released all the pressure from the fuel lines. It's possible there isn't enough fuel in the rail. Try turning the key to the on position (not start) and let the fuel pump prime. Then turn it off and repeat a few times. Then try to start it. Good luck.

 

i changed the filter after it wouldn't start, i was hoping it was plugged up, but it wasn't, and i did try and prime the system a few times before i tried to start it, the fuel pump sounded fine.

 

Start with the basics, check spark, fuel pressure, then compression....only other thing you need to make it run is timing.

Is your security light on or flashing?

 

what is the best way to check for spark?

 

Pull a plug wire off of the #1 cylinder and hold it right next to a good ground while someone cranks the car. The spark should arc from the wire to the ground. Or if you have a jumper wire with an alligator clip on the end of it, clip it on the boot of the plug wire and crank the car and watch for spark.

 

Did you check all your fuses?

 

Are you sure there's gas in the tank Nathan? LOL.....seriously.

You'll need to go back to the basics required for combustion....fuel, air, spark, timing, compression. Check for spark as someone already suggested. I have a tester you can borrow if needed. Check for good fuel pressure at the rail....I also have a gauge you can use. Checking all the fuses is also a good idea at this point. You may even want to do a compression test to verify you don't have a valve hanging open or something on one cylinder.

I also read a post here recently about a broken coolant temp sensor causing problems similar to yours, and also possibly the VATS? But maybe the VATS was just an issue on 'vettes. But if there's no security light on then it not the VATS.

I'm still inclined to think you either have a vacuum leak (maybe cracked manifold) or a bad spark plug that's causing your misfires and crappy idle though.

 

Crank position sensor? behind starter is it plugged in?

 

it's got spark, and 52 psi of fuel pressure, i guess i will check the compression tomorrow

 

Well if you have spark then your CKP sensor is working fine. If you DO have compression, then you have a problem with timing, but obviously if it ran before then I doubt that's it. Only other thing to do is check the injectors. I'd check the injectors fuse(s) as well.

 

i checked all of the fuses last night also. i am waiting on help to get here to do the compression test.

 

PCM just took a ****.

 

compression test numbers

1 - 170
2 - 200
3 - 155
4 - 180
5 - 165
6 - 155
7 - 165
8 - 160

any ideas?

 

Compression numbers look good....could be closer but its enough to start the car. Get your hands on a set of noid lights and check for injector pulse.

 

Please take my advice for your situation. I have had this happen to me when I did heads, cam, lifters, ect. ect. ect. Although the advice that people posted up for you is good, I would take 20 minutes and pull your intake off. Chances are good that you pinched the cam position sensor harness under the manifold. The harness itself is not big enough to cause a vacum leak so initially, it would hard to determine if it is indeed under the manifold. If the harness is pinched, it may have taken the numerous starts to finally break the connection. The computer relies on the crank and cam position sensors to start the car. Once the car is running, the computer takes over and relies less on the cam sensor. Furthermore, if the connection fails while the car is still running, the car will CONTINUE to run, however, once the car is shutdown with that broken connection, it will not start becuase the computer does not recognize where the cam is in relation to the crank. Checking for spark in this case is useless because the spark is driven off the crank. (obviously by computer not a distributor)
The harness (if that is indeed your problem) may have failed during the last time the car ran, or when the motor was turned off. I had the same thing happen to me. Car started many times, then it didn't. I went through everything your going through. I had good compression, spark, fuel, injector pulse...then I just decided to pull the intake knowing thats where the harness for the cam position sensor ran. Once I pulled the intake off, the harness was pinched and broken. I repaired the harness, re-installed the intake, and the car fired right up. Good luck

 

Good advice.....